Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Pre-Tax Amount
Other Comprehensive Income (Loss), before Tax		$ 1,831	$ 12,833
Tax (Expense) Benefit
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		643	4,492
Net of Tax Amount
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		1,188	8,341
Accumulated Net Investment Gain (Loss) Attributable to Parent
Pre-Tax Amount
Change in net unrealized gains/(losses) on securities available-for-sale		1,662	9,033
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	370	0
Tax (Expense) Benefit
Change in net unrealized gains/(losses) on securities available-for-sale		(584)	(3,162)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	130	0
Net of Tax Amount
Change in net unrealized gains/(losses) on securities available-for-sale		1,078	5,871
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	240	0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Pre-Tax Amount
Other Comprehensive Income (Loss), before Tax		539	3,800
Tax (Expense) Benefit
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		189	1,330
Net of Tax Amount
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		$ 350	$ 2,470

[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 and have affected certain lines in the consolidated statement 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.