Acquisitions - Business Acquisition, Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Combinations [Abstract]
Interest income	$ 108,765	$ 99,288	$ 312,091	$ 289,060
Non-interest income	38,274	39,811	116,171	114,881
Total revenues	147,039	139,099	428,262	403,941
Net income	$ 34,903	$ 28,769	$ 94,017	$ 44,317
EPS - basic (in dollars per share)	$ 0.52	$ 0.52	$ 1.55	$ 0.79
EPS - diluted (in dollars per share)	$ 0.51	$ 0.51	$ 1.53	$ 0.79