Defined Benfit Plan (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended									6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]	Dec. 31, 2013 Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]	Jun. 30, 2014 Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2013 Significant Observable Inputs, Level 2 [Member]	Jun. 30, 2014 Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2013 Significant Unobservable Inputs, Level 3 [Member]	Jun. 30, 2014 Equity Securities [Member]	Dec. 31, 2013 Equity Securities [Member]	Jun. 30, 2014 Fixed Income Securities [Member]	Dec. 31, 2013 Fixed Income Securities [Member]	Jun. 30, 2014 Cash and cash equivalents [Member]	Dec. 31, 2013 Cash and cash equivalents [Member]	Jun. 30, 2014 Cash and cash equivalents [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]	Dec. 31, 2013 Cash and cash equivalents [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]	Jun. 30, 2014 Cash and cash equivalents [Member] Significant Observable Inputs, Level 2 [Member]	Dec. 31, 2013 Cash and cash equivalents [Member] Significant Observable Inputs, Level 2 [Member]	Jun. 30, 2014 Cash and cash equivalents [Member] Significant Unobservable Inputs, Level 3 [Member]	Dec. 31, 2013 Cash and cash equivalents [Member] Significant Unobservable Inputs, Level 3 [Member]	Jun. 30, 2014 Actively Managed [Member] All Cap Equity Fund [Member]		Dec. 31, 2013 Actively Managed [Member] All Cap Equity Fund [Member]		Jun. 30, 2014 Actively Managed [Member] All Cap Equity Fund [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] All Cap Equity Fund [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] All Cap Equity Fund [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] All Cap Equity Fund [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] All Cap Equity Fund [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] All Cap Equity Fund [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Large Cap Equity [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Large Cap Equity [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Large Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Large Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Large Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Large Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Large Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Large Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Mid Cap Equity [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Mid Cap Equity [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Mid Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Mid Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Mid Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Mid Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Mid Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Mid Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Small Cap Equity [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Small Cap Equity [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Small Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Small Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Small Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Small Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] U.S. Small Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] U.S. Small Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Actively Managed [Member] Non-U.S. Large Cap Equity [Member]		Dec. 31, 2013 Actively Managed [Member] Non-U.S. Large Cap Equity [Member]		Jun. 30, 2014 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] Non-U.S. Large Cap Equity [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Actively Managed [Member] REIT [Member]		Dec. 31, 2013 Actively Managed [Member] REIT [Member]		Jun. 30, 2014 Actively Managed [Member] REIT [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Actively Managed [Member] REIT [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Actively Managed [Member] REIT [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Actively Managed [Member] REIT [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Actively Managed [Member] REIT [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Actively Managed [Member] REIT [Member] Significant Unobservable Inputs, Level 3 [Member]		Jun. 30, 2014 Fixed Income [Member]		Dec. 31, 2013 Fixed Income [Member]		Jun. 30, 2014 Fixed Income [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Dec. 31, 2013 Fixed Income [Member] Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]		Jun. 30, 2014 Fixed Income [Member] Significant Observable Inputs, Level 2 [Member]		Dec. 31, 2013 Fixed Income [Member] Significant Observable Inputs, Level 2 [Member]		Jun. 30, 2014 Fixed Income [Member] Significant Unobservable Inputs, Level 3 [Member]		Dec. 31, 2013 Fixed Income [Member] Significant Unobservable Inputs, Level 3 [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 1,051	$ 1,239	$ 2,111	$ 2,478
Interest cost	1,652	1,475	3,303	2,950
Other cost	625	1,208	1,256	2,416
Expected return on assets	(1,674)	(1,380)	(3,341)	(2,760)
Net periodic benefit cost	1,654	2,542	3,329	5,084
Plan Assets [Abstract]
Fair value of plan assets	99,291		99,291		95,353	58,742	55,532	40,549	39,821	0	0					6,337	9,127	6,337	9,127	0	0	0	0	2,618	[1]	283	[1]	2,592	[1]	266	[1]	26	[1]	17	[1]	0	[1]	0	[1]	35,699	[1]	32,286	[1]	35,699	[1]	32,286	[1]	0	[1]	0	[1]	0	[1]	0	[1]	5,783	[1]	5,551	[1]	5,783	[1]	5,551	[1]	0	[1]	0	[1]	0	[1]	0	[1]	3,219	[1]	3,236	[1]	3,219	[1]	3,236	[1]	0	[1]	0	[1]	0	[1]	0	[1]	5,112	[1]	5,066	[1]	5,112	[1]	5,066	[1]	0	[1]	0	[1]	0	[1]	0	[1]	4,616	[1]	3,913	[1]	0	[1]	0	[1]	4,616	[1]	3,913	[1]	0	[1]	0	[1]	35,907	[2]	35,891	[2]	0	[2]	0	[2]	35,907	[2]	35,891	[2]	0	[2]	0	[2]
Target plan asset allocations												55.00%	55.00%	45.00%	45.00%
Employer Contributions [Abstract]
Estimated employer contributions for the current fiscal year	5,946		5,946
Actual employer contribution amount in current period	$ 1,819		$ 1,819

[1] Actively managed portfolio of securities with the goal to exceed the stated benchmark performance.

[2] Actively managed portfolio of fixed income securities with the goal to exceed the Barclays 1-5 Year Government/Credit, Barclays Intermediate Government/Credit, and Merrill Lynch Preferred Stock Fixed Rate.