Loans and Allowance for Credit Losses Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Receivables [Abstract]
Allowance for loan losses	$ 168,679	$ 169,054	$ 184,144
Reserve for unfunded lending commitments	2,646	2,358	1,787
Allowance for credit losses	$ 171,325	$ 171,412	$ 185,931	$ 204,917