Loans and Allowance for Credit Losses Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Allowance for loan losses	$ 162,546	$ 163,841	$ 169,054	$ 167,485	$ 177,701	$ 184,144
Reserve for unfunded lending commitments	2,562		2,358
Allowance for credit losses	$ 165,108	$ 166,065	$ 171,412	$ 169,453	$ 179,658	$ 185,931