Securities (Details) - Changes In Credit Losses Recognized In Earnings $ in Thousands		12 Months Ended
		Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) security	Dec. 31, 2014 USD ($) security
Changes in Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance		$ 23,345	$ 23,516	$ 32,422
OTTI included in earnings:
Losses on securities that previously had OTTI	[1]	0	0	28
Losses on securities that did not previously have OTTI	[1]	0	0	0
Ending balance		23,345	23,345	23,516
Reduction for securities sales	[2]	$ 0	$ 171	8,934
CMOs
OTTI included in earnings:
Number of CMOs sold | security			1
Reduction for securities sales			$ 1,300
CDOs
OTTI included in earnings:
Reduction for securities sales				$ 1,300
Number Of CDOs Sold | security				1
Municipal securities
OTTI included in earnings:
Reduction for securities sales				$ 357
Number Of Municipal securities sold | security				1

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

[2] These reductions were driven by the sale of one CMO with a carrying value of $1.3 million during the year ended December 31, 2015 and one CDO with a carrying value of $1.3 million and one municipal security with a carrying value of $357,000 during the year ended December 31, 2014