CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 17,674	$ 13,199	$ 33,885	$ 24,981
Other comprehensive income (loss), net of tax:
Net change in fair value of securities available for sale	(3,112)	1,828	(13,526)	2,229
Net change in fair value of cash flow hedges	365	(448)	1,254	(350)
Net change in defined benefit plan obligations	360	(4)	720	209
Total other comprehensive income (loss), net of tax	(2,387)	1,376	(11,552)	2,088
Total comprehensive income	$ 15,287	$ 14,575	$ 22,333	$ 27,069