Consolidated Statements of Comprehensive Income - AOCI - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income	$ 14,987	$ 37
Accumulated Unrealized Gain (Loss) on Securities Available- for-Sale
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(10,271)	(2,950)
Other comprehensive income	12,348	(481)
Ending balance	2,077	(3,431)
Accumulated Unrealized Gain (Loss) on Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,468)	(1,138)
Other comprehensive income	2,639	518
Ending balance	171	(620)
Unrecognized Net Pension Costs
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(15,650)	(11,767)
Other comprehensive income	0	0
Ending balance	(15,650)	(11,767)
Total Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(28,389)	(15,855)
Other comprehensive income	14,987	37
Ending balance	$ (13,402)	$ (15,818)