Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Receivables [Abstract]
Balance at beginning of year	$ 185,931	$ 204,917	$ 225,439
Loans charged off	32,157	44,593	80,212
Recoveries of loans previously charged off	15,388	13,107	19,190
Net loans charged off	16,769	31,486	61,022
Provision for credit losses	2,250	12,500	40,500
Balance at end of year	$ 171,412	$ 185,931	$ 204,917