Accumulated Other Comprehensive Income (Loss) - Summary of Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	$ (1,630)	$ (6,410)
Other comprehensive income before reclassifications	1,274	6,528
Amounts reclassified from accumulated other comprehensive income	(1,006)	(1,748)
Period change	268	4,780	$ (911)
AOCI - ending balance	(1,362)	(1,630)	(6,410)
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	14,098	1,566
Other comprehensive income before reclassifications	(37)	14,860
Amounts reclassified from accumulated other comprehensive income	(1,736)	(2,328)
Period change	(1,773)	12,532
AOCI - ending balance	12,325	14,098	1,566
Unrealized Gains (Losses) on Securities Available for Sale for which a Portion of Other-Than-Temporary Impairment has been Recognized in Income
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	$ 0	(1,847)
Other comprehensive income before reclassifications		$ 1,847
Amounts reclassified from accumulated other comprehensive income
Period change	$ 0	$ 1,847
AOCI - ending balance	0	0	(1,847)
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	(2,182)	(501)
Other comprehensive income before reclassifications	(1,093)	(2,599)
Amounts reclassified from accumulated other comprehensive income	928	918
Period change	(165)	(1,681)
AOCI - ending balance	(2,347)	(2,182)	(501)
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Income [Roll Forward]
AOCI - beginning balance	(13,546)	(5,628)
Other comprehensive income before reclassifications	2,404	(7,580)
Amounts reclassified from accumulated other comprehensive income	(198)	(338)
Period change	2,206	(7,918)
AOCI - ending balance	$ (11,340)	$ (13,546)	$ (5,628)