Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 838	$ 624
Defined Benefit Plan, Interest Cost	1,380	1,470
Defined Benefit Plan, Expected Return on Plan Assets	(1,478)	(1,375)
Defined Benefit Plan, Amortization of Losses	981	691
Defined Benefit Plan, Amortization of Prior Service Cost	28	28
Defined Benefit Plan, Net Periodic Benefit Cost	1,749	1,438
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			6,610
Defined Benefit Plan, Contributions by Employer	4,130
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	13	4
Defined Benefit Plan, Interest Cost	56	71
Defined Benefit Plan, Expected Return on Plan Assets	0	0
Defined Benefit Plan, Amortization of Losses	47	31
Defined Benefit Plan, Amortization of Prior Service Cost	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	116	106
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			719
Defined Benefit Plan, Contributions by Employer	$ 232