Pension and Other Postretirement Benefit Plans Components of Net Periodic Pension Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Service Cost	$ 1,787	$ 1,445	$ 1,582
Defined Benefit Plan, Interest Cost	1,192	1,756	1,676
Defined Benefit Plan, Expected Return on Plan Assets	(986)	(1,303)	(1,291)
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	(96)	(87)	(87)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(85)	7	159
Defined Benefit Plan, Amortization of Gains (Losses)	727	540	468
Defined Benefit Plan, Net Periodic Benefit Cost	$ 2,539	$ 2,358	$ 2,507