Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Pre-Tax Amount
Other comprehensive income (loss), before tax		$ (8,853)	$ 1,831
Tax (Expense) Benefit
Other comprehensive income (loss), tax		1,880	(643)
Net of Tax Amount
Other Comprehensive Income/(Loss)		(6,973)	1,188
Accumulated Net Investment Gain (Loss) Attributable to Parent
Pre-Tax Amount
Change in net unrealized gains/(losses) on debt securities available-for-sale		(9,474)	1,662
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	(370)
Tax (Expense) Benefit
Change in net unrealized gains/(losses) on debt securities available-for-sale		2,012	(584)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	130
Net of Tax Amount
Change in net unrealized gains/(losses) on debt securities available-for-sale		(7,462)	1,078
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	(240)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Pre-Tax Amount
Other comprehensive income (loss), before tax		621	539
Tax (Expense) Benefit
Other comprehensive income (loss), tax		(132)	(189)
Net of Tax Amount
Other Comprehensive Income/(Loss)		$ 489	$ 350

[1] Reclassification adjustments are comprised of realized security gains or losses. The realized gains or losses have been reclassified out of accumulated other comprehensive income/(loss) and have affected certain lines in the Consolidated Statements of Comprehensive Income as follows; the pre-tax amount is included in securities gains/losses-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income.