CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 17,511	$ 12,962	$ 51,396	$ 37,943
Other comprehensive income (loss), net of tax:
Net change in fair value of securities available for sale	(4,531)	1,094	(18,057)	3,323
Net change in fair value of cash flow hedges	155	(13)	1,409	(364)
Net change in defined benefit plan obligations	361	217	1,081	427
Total other comprehensive income (loss), net of tax	(4,015)	1,298	(15,567)	3,386
Total comprehensive income	$ 13,496	$ 14,260	$ 35,829	$ 41,329