Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 92,349	$ 82,064	$ 69,306
Unrealized holding (losses) gains:
Before tax	(19,204)	(9,824)	37,173
Tax effect	7,682	3,906	(14,918)
Net of tax	(11,522)	(5,918)	22,255
Reclassification of net gains included in net income:
Before tax	1,420	2,373	8,097
Tax effect	(568)	(970)	(3,311)
Net of tax	852	1,403	4,786
Net unrealized holding (losses) gains	(12,374)	(7,321)	17,469
Derivative Instruments
Before tax	2,175	(2,233)	(1,930)
Tax effect	(883)	903	792
Net of tax	1,292	(1,330)	(1,138)
Unrealized holding losses:
Before tax	(2,002)	(6,570)	(9,127)
Tax effect	563	2,687	3,733
Net of tax	(1,439)	(3,883)	(5,394)
Total other comprehensive (loss) income	(12,521)	(12,534)	10,937
Total comprehensive income	$ 79,828	$ 69,530	$ 80,243