Benefits - Weighted Average Discount Rate (Details)	9 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2012 Successor [Member] Pension Plans, Defined Benefit [Member]	Dec. 31, 2012 Successor [Member] Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2012 Successor [Member] Other Postretirement Benefit Plans, Defined Benefit [Member]	Mar. 25, 2012 Predecessor [Member] Pension Plans, Defined Benefit [Member]	Dec. 31, 2011 Predecessor [Member] Pension Plans, Defined Benefit [Member]	Dec. 31, 2010 Predecessor [Member] Pension Plans, Defined Benefit [Member]	Mar. 25, 2012 Predecessor [Member] Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2011 Predecessor [Member] Other Postretirement Benefit Plans, Defined Benefit [Member]	Dec. 31, 2010 Predecessor [Member] Other Postretirement Benefit Plans, Defined Benefit [Member]
Assumptions used in calculating benefit obligation [Abstract]
Discount Rate	3.67%	3.37%	3.37%	4.10%	4.14%		4.09%	4.14%
Rate of Compensation Increase	3.17%			3.02%	3.02%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount Rate	4.10%	3.05%		4.14%	5.35%	5.82%	4.14%	5.36%	5.85%
Expected long term return on assets, tax exempt accounts	8.25%		7.00%	8.25%	8.25%	8.25%	7.00%	7.00%	7.00%
Expected long term return on assets, taxable accounts			4.50%				4.50%	4.50%	5.00%
Rate of Compensation Increase	3.02%			3.02%	3.02%	3.24%