Loans and Allowance for Credit Losses Non-Performing Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Receivables [Abstract]
Non-accrual loans	$ 129,152	$ 121,080
Accruing loans 90 days or more past due	20,353	17,402
Total non-performing loans	149,505	138,482
Other real estate owned (OREO)	12,763	12,022
Total non-performing assets	$ 162,268	$ 150,504