I have modified your code a bit and tried to login as follows:
from selenium import webdriver
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException
options = webdriver.ChromeOptions()
options.add_argument('start-maximized')
options.add_argument('disable-infobars')
options.add_argument('--disable-extensions')
driver = webdriver.Chrome(chrome_options=options, executable_path=r'C:\WebDrivers\chromedriver.exe')
driver.get("https://login.onlinebanking.suntrust.com/olb/login")
WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.CSS_SELECTOR, "input.suntrust-input-text.ng-pristine.ng-valid.ng-touched#userId"))).send_keys("username")
driver.find_element_by_css_selector("input.suntrust-input-text.ng-untouched.ng-pristine.ng-valid#password").send_keys("password")
driver.find_element_by_css_selector("button.suntrust-sign-on.suntrust-button-text>span").click()
But was still unable to login.
Now on inspecting the DOM Tree of SUNTRUST - Online Banking Sign On login page you will find the following tags within the <body> tag:
<script type="text/javascript" src="dist/runtime.7d6aba6a1596ee0b757c.js"></script>
<script type="text/javascript" src="dist/polyfills.65913a8531010587b6fe.js"></script>
<script type="text/javascript" src="dist/scripts.46e57c2d57ad1b3d210d.js"></script>
<script type="text/javascript" src="dist/vendor.43f2240dc35276d98b10.js"></script>
<script type="text/javascript" src="dist/main.5d227767baa37ef78819.js"></script>
Snapshot

The presence of the phrase dist is a clear indication that the website is protected by Bot Management service provider Distil Networks and the navigation by ChromeDriver gets detected and subsequently blocked.
Distil
As per the article There Really Is Something About Distil.it...:
Distil protects sites against automatic content scraping bots by observing site behavior and identifying patterns peculiar to scrapers. When Distil identifies a malicious bot on one site, it creates a blacklisted behavioral profile that is deployed to all its customers. Something like a bot firewall, Distil detects patterns and reacts.
Further,
"One pattern with **Selenium** was automating the theft of Web content", Distil CEO Rami Essaid said in an interview last week. "Even though they can create new bots, we figured out a way to identify Selenium the a tool they're using, so we're blocking Selenium no matter how many times they iterate on that bot. We're doing that now with Python and a lot of different technologies. Once we see a pattern emerge from one type of bot, then we work to reverse engineer the technology they use and identify it as malicious".
Reference
You can find a couple of relevant discussions in: