Acquisition Acquisition (Details 2) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	May 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Combinations [Abstract]
Goodwill	$ 19,022	$ 274,202		$ 274,202		$ 255,353
Business Combination, Acquired Receivables, Gross Contractual Amount	183,700
Business Combinatoin, Acquired Receivables, Fair Value Adjustment	4,300
Business Combination, Acquired Receivables, Contractual Adjustments	5,100
Conversion Related Expenses		$ 24	$ (69)	$ 1,634	$ 10,412
Payments to Acquire Businesses, Gross	$ 17,400
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	2,745,098
Business Combination, Acquired Receivable, Fair Value	$ 184,506
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits	$ 141,281