Loans and Allowance for Credit Losses Non-Performing Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Non-accrual loans	$ 128,572	$ 124,749
Loans 90 days or more past due and still accruing	11,106	10,010
Total non-performing loans	139,678	134,759
Other real estate owned	10,518	9,823
Total non-performing assets	$ 150,196	$ 144,582