Commitments and Contingencies (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Mar. 31, 2011 Predecessor	Dec. 31, 2010 Predecessor
Operating Leases
Gross rental expense	$ 125	$ 93	$ 58	$ 200
Sublease rental income received	10	8	4	15
Operating leases:
2013		55
2014		36
2015		30
2016		25
2017		20
2018 and thereafter		39
Total future minimum payments		205
Minimum sublease rentals due in the future under non-cancelable subleases		32
Purchase Obligations
Total purchase commitments		179
2013		47
2014 through 2015		63
2016 through 2017		56
2018 and thereafter		$ 13