Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value Measurements (Textual) [Abstract]
Impaired loans not covered under loss-share agreements	$ 4,518		$ 9,608
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific reserve included in allowance for loan losses	47,355		46,211
Changes in fair value, gain (loss)	4,177	$ 6,092
Impaired Loans, Not Covered
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific reserve included in allowance for loan losses	$ 554		$ 357