Loans and Allowance for Credit Losses Non-Performing Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Receivables [Abstract]
Non-accrual loans	$ 123,345	$ 120,133
Loans 90 days or more past due and still accruing	13,124	11,505
Total non-performing loans	136,469	131,638
Other real estate owned (OREO)	10,542	12,815
Total non-performing assets	$ 147,011	$ 144,453