Acquisitions - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Net interest and other income	$ 342,159	$ 258,970	$ 246,622
Net income	$ 72,316	$ 71,722	$ 58,257
Basic earnings per share (in dollars per share)	$ 1.58	$ 1.58	$ 1.30
Diluted earnings per share (in dollars per share)	$ 1.55	$ 1.56	$ 1.29