Parent Company Condensed Financial Information - Statements of Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Information [Line Items]
Interest expense on long-term debt	$ 670	$ 790	$ 617
Net Income	71,392	67,081	57,910
Parent Company
Condensed Financial Information [Line Items]
Dividends from subsidiaries	34,134	75,413	46,414
Investment income	17	19	19
Interest expense on long-term debt	854	773	759
Other expenses	2,315	2,138	2,014
Income before Equity in Undistributed Net Income of Subsidiaries	30,982	72,521	43,660
Bank subsidiary	40,051	(5,064)	13,351
Nonbank subsidiaries	359	(376)	899
Net Income	$ 71,392	$ 67,081	$ 57,910