Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 728	$ 614	$ 1,566	$ 1,238
Defined Benefit Plan, Interest Cost	1,398	1,457	2,778	2,927
Defined Benefit Plan, Expected Return on Plan Assets	(1,463)	(1,368)	(2,941)	(2,743)
Defined Benefit Plan, Amortization of Losses	991	689	1,972	1,380
Defined Benefit Plan, Amortization of Prior Service Cost	104	28	132	56
Defined Benefit Plan, Net Periodic Benefit Cost	1,758	1,420	3,507	2,858
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					6,610
Defined Benefit Plan, Contributions by Employer			5,240
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	4	5	17	9
Defined Benefit Plan, Interest Cost	36	71	92	142
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Amortization of Losses	(31)	30	16	61
Defined Benefit Plan, Amortization of Prior Service Cost	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	9	106	125	212
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					719
Defined Benefit Plan, Contributions by Employer			$ 352