Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Balance at beginning of year	$ 171,412	$ 185,931	$ 204,917
Loans charged off	(33,927)	(32,157)	(44,593)
Recoveries of loans previously charged off	20,658	15,388	13,107
Net loans charged off	(13,269)	(16,769)	(31,486)
Provision for credit losses	13,182	2,250	12,500
Balance at end of year	$ 171,325	$ 171,412	$ 185,931