Benefit Plans - Net Periodic Benefit Expense (Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended				11 Months Ended	12 Months Ended		11 Months Ended	12 Months Ended		1 Months Ended
	Jun. 30, 2010	Dec. 31, 2012 Pension Plans	Dec. 31, 2011 Pension Plans	Dec. 31, 2012 Postretirement Plans	Dec. 31, 2011 Postretirement Plans	Dec. 31, 2010 Successor Company Pension Plans	Dec. 31, 2012 Successor Company Pension Plans	Dec. 31, 2011 Successor Company Pension Plans	Dec. 31, 2010 Successor Company Postretirement Plans	Dec. 31, 2012 Successor Company Postretirement Plans	Dec. 31, 2011 Successor Company Postretirement Plans	Jan. 31, 2010 Predecessor Company Pension Plans	Jan. 31, 2010 Predecessor Company Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost		$ 10,693	$ 12,707	$ 0	$ 26	$ 12,432	$ 10,693	$ 12,707	$ 107	$ 0	$ 26	$ 1,124	$ 10
Expected return on plan assets						(12,201)	(13,419)	(14,500)				(1,385)
Settlement loss						17	3,746	2,748				0
Amortization of unrecognized prior service cost						0	0	0				81
Curtailment gain	3,800					(3,754)	0	0				0
Amortization of unrecognized net loss						0	856	2	(291)	0	(1,111)	122	(21)
Net periodic benefit expense (income)						$ (3,506)	$ 1,876	$ 957	$ (184)	$ 0	$ (1,085)	$ (58)	$ (11)