CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 69,118	$ 68,432	$ 45,925
Other comprehensive income (loss), net of tax:
Net change in fair value of available for sale debt securities	19,988	(9,228)	621
Net change in fair value of cash flow hedges	(984)	619	(52)
Net change in defined benefit plan obligations	(1,932)	3,810	(97)
Total other comprehensive income (loss), net of tax	17,072	(4,799)	472
Total comprehensive income	$ 86,190	$ 63,633	$ 46,397