CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	12 Months Ended		9 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 25, 2012
Statement of Income and Comprehensive Income [Line Items]
Net income (loss)	$ (3)	$ (535)
Successor
Statement of Income and Comprehensive Income [Line Items]
Net income (loss)	(3)	(535)	39
Other comprehensive income (loss), net of tax:
Change in fair value of interest rate hedges	0	0	0
Reclassification of unrealized loss on interest rate hedges into earnings	0	0	0
Change in fair value of commodity hedges	0	(3)	(4)
Reclassification of unrealized loss on interest rate hedges into earnings	0	6	1
Actuarial gain (loss) relating to postretirement benefits	(3)	25	(22)
Reclassification of prior service credit relating to other postretirement benefits into earnings	0	0	0
Total other comprehensive income (loss)	(3)	28	(25)
Comprehensive income (loss)	(6)	(507)	14
Predecessor
Statement of Income and Comprehensive Income [Line Items]
Net income (loss)				50
Other comprehensive income (loss), net of tax:
Change in fair value of interest rate hedges				4
Reclassification of unrealized loss on interest rate hedges into earnings				5
Change in fair value of commodity hedges				3
Reclassification of unrealized loss on interest rate hedges into earnings				(1)
Actuarial gain (loss) relating to postretirement benefits				0
Reclassification of prior service credit relating to other postretirement benefits into earnings				1
Total other comprehensive income (loss)				12
Comprehensive income (loss)				$ 62