CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) [Abstract]
Net Income	$ 14,745	$ 11,157
Other comprehensive income (loss):
Change in unrealized holding loss on securities held-to-maturity and transferred securities	0	34
Change in unrealized holding loss on securities available-for-sale	(2,558)	120
Change in pension and other postretirement obligations	155	302
Change in unrealized gain on derivative asset	2,016	315
Other comprehensive gain (loss) before income taxes	(387)	771
Deferred tax expense (benefit)	(112)	346
Other comprehensive income (loss), net of tax	(275)	425
Total comprehensive income	$ 14,470	$ 11,582