Pension Benefits (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended									12 Months Ended										12 Months Ended			12 Months Ended																				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 30, 2010	Apr. 30, 2010	Apr. 30, 2010 Predecessor	Dec. 31, 2009 Predecessor	Dec. 31, 2012 Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Significant Unobservable Inputs (Level 3)	Dec. 31, 2011 Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Large-Cap Disciplined Equity	Dec. 31, 2011 Large-Cap Disciplined Equity	Dec. 31, 2012 Large-Cap Disciplined Equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Large-Cap Disciplined Equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Small/Mid-Cap Equity	Dec. 31, 2011 Small/Mid-Cap Equity	Dec. 31, 2012 Small/Mid-Cap Equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Small/Mid-Cap Equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 International equity	Dec. 31, 2012 International equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 International equity Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Domestic equity securities	Dec. 31, 2012 Fixed income securities	Dec. 31, 2012 Long Duration Fixed Income	Dec. 31, 2011 Long Duration Fixed Income	Dec. 31, 2012 Long Duration Fixed Income Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Long Duration Fixed Income Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Core Fixed Income	Dec. 31, 2012 Core Fixed Income Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 High Yield	Dec. 31, 2011 High Yield	Dec. 31, 2012 High Yield Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 High Yield Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Emerging Markets Debt	Dec. 31, 2011 Emerging Markets Debt	Dec. 31, 2012 Emerging Markets Debt Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Emerging Markets Debt Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Hedge Fund of Funds	Dec. 31, 2011 Hedge Fund of Funds	Dec. 31, 2012 Hedge Fund of Funds Significant Unobservable Inputs (Level 3)	Dec. 31, 2011 Hedge Fund of Funds Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Alternatives	Dec. 31, 2012 Cash	Dec. 31, 2012 Cash Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Other Investments	Dec. 31, 2012 Other Investments Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plan
Target allocation (as a percent)																				13.00%			25.00%	37.00%																			25.00%
Assets measured at fair value	$ 164,048	$ 146,630	$ 143,818	$ 137,374	$ 137,374	$ 137,374	$ 131,110	$ 141,430	$ 125,034	$ 22,618	$ 21,596	$ 37,942	$ 39,335	$ 37,942	$ 39,335	$ 9,212	$ 8,869	$ 9,212	$ 8,869	$ 21,618	$ 21,618	$ 17,915			$ 46,084	$ 45,961	$ 46,084	$ 45,961	$ 3,081	$ 3,081	$ 6,145	$ 8,665	$ 6,145	$ 8,665	$ 4,638	$ 4,289	$ 4,638	$ 4,289	$ 22,618	$ 21,596	$ 22,618	$ 21,596		$ 4,510	$ 4,510	$ 8,200	$ 8,200
Expected long term rate of return on plan assets (as a percent)	7.50%	7.50%	7.50%
Rollforward of the balances of plan assets that are valued using level 3 inputs (in thousands)
Beginning balance	146,630	143,818		137,374	137,374	137,374	131,110	141,430	125,034	21,596	20,700	37,942	39,335	37,942	39,335	9,212	8,869	9,212	8,869	17,915	21,618	17,915			46,084	45,961	46,084	45,961	3,081	3,081	6,145	8,665	6,145	8,665	4,638	4,289	4,638	4,289	22,618	21,596	22,618	21,596		4,510	4,510	8,200	8,200
Actual return on plan assets:
Relating to assets still held at the reporting date										1,022	(143)
Relating to assets sold during the period											39
Purchases, sales and settlements, net											1,000
Fair value of plan assets at end of period	164,048	146,630	143,818	137,374	137,374	137,374	131,110	141,430	125,034	22,618	21,596	37,942	39,335	37,942	39,335	9,212	8,869	9,212	8,869	21,618	21,618	17,915			46,084	45,961	46,084	45,961	3,081	3,081	6,145	8,665	6,145	8,665	4,638	4,289	4,638	4,289	22,618	21,596	22,618	21,596		4,510	4,510	8,200	8,200
Estimated Future Employer Contributions
Employer contributions for fiscal year 2012 (expected) to plan trusts	6,000
Expected benefit payments:
2013	8,174
2014	8,575
2015	9,035
2016	9,460
2017	9,863
2018-2022	57,293
Total benefit payments	$ 102,400