Allowance for Credit Losses - Provision for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Receivables [Abstract]
Provision for loan losses	$ 3,706	$ 6,592	$ 11,562	$ 17,294
Provision for unfunded letters of credit	(1,606)	550	(1,462)	796
Total provision for credit losses	$ 2,100	$ 7,142	$ 10,100	$ 18,090