Loans and Allowance for Credit Losses Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Receivables [Abstract]
Allowance for loan losses	$ 162,526	$ 162,546	$ 169,054	$ 167,136	$ 167,485	$ 184,144
Reserve for unfunded lending commitments	2,643		2,358
Allowance for credit losses	$ 165,169	$ 165,108	$ 171,412	$ 169,395	$ 169,453	$ 185,931