Investment Securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract]
Carrying value of securities pledged to secure public deposits, derivatives and other secured borrowings | $	$ 918,000,000	$ 925,000,000
Number of available for sale securities in unrealized loss position | security	51
Number of held-to-maturity securities in unrealized loss position | security	33
Other-than-temporary impairment charges | $	$ 0	$ 0	$ 0