Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions		Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Dec. 31, 2018				57,749,464
Beginning balance at Dec. 31, 2018		$ 1,570		$ 1	$ 1,522	$ (47)	$ 94
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		160					160
Total other comprehensive income		52				52
Shares issued from Employee Stock Purchase Plan (in shares)				84,036
Shares issued from the Employee Stock Purchase Plan		0
Bancorp Dividends Declared and paid (in shares)				280
Bancorp Dividends Declared and paid		(7)					(7)
Stock-based compensation (in shares)				194,266
Stock-based compensation		9			9
Repurchase of shares (in shares)	[1]			(1,517,705)
Repurchase of shares	[1]	(50)			(50)
Ending balance (in shares) at Sep. 30, 2019				56,510,341
Ending balance at Sep. 30, 2019		1,734		$ 1	1,481	5	247
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		63
Total other comprehensive income		13
Ending balance (in shares) at Sep. 30, 2019				56,510,341
Ending balance at Sep. 30, 2019		1,734		$ 1	1,481	5	247
Beginning balance (in shares) at Dec. 31, 2019				56,631,236
Beginning balance at Dec. 31, 2019		1,788	$ (23)	$ 1	1,483	1	303	$ (23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		384					384
Total other comprehensive income		45				45
Shares issued from Employee Stock Purchase Plan (in shares)				149,789
Shares issued from the Employee Stock Purchase Plan		0
Bancorp Dividends Declared and paid (in shares)				583
Bancorp Dividends Declared and paid		(9)					(9)
Stock-based compensation (in shares)				368,862
Stock-based compensation		10			10
Repurchase of shares	[1]	0
Ending balance (in shares) at Sep. 30, 2020				57,150,470
Ending balance at Sep. 30, 2020		2,195		$ 1	1,493	46	655
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		222
Total other comprehensive income		0
Ending balance (in shares) at Sep. 30, 2020				57,150,470
Ending balance at Sep. 30, 2020		$ 2,195		$ 1	$ 1,493	$ 46	$ 655

[1] Includes dividend reinvestment shares