Securities - Changes In Credit Losses Recognized In Earnings (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) security	Dec. 31, 2016 USD ($)
Changes in Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance		$ 0	$ 23,345	$ 23,345
OTTI included in earnings:
Reduction for securities sales	[1],[2]	0	(23,345)	0
Ending balance		$ 0	0	$ 23,345
CDOs
OTTI included in earnings:
Reduction for securities sales			$ (47,700)
Number of CDOs sold (security) | security			11

[1] Included in net securities gains (losses) in the Consolidated Statements of Income.

[2] These reductions were driven by the sale of 11 CDOs with a carrying value of $47.7 million during the year ended December 31, 2017.