Benefits - Obligations and funded status table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended		9 Months Ended		3 Months Ended	12 Months Ended		9 Months Ended
	Mar. 25, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Successor [Member]	Mar. 25, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member] Successor [Member]	Mar. 25, 2012 Pension Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2011 Pension Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2010 Pension Plans, Defined Benefit [Member] Predecessor [Member]	Dec. 31, 2012 Pension Plans, Defined Benefit [Member] Successor [Member]	Mar. 25, 2012 Pension Plans, Defined Benefit [Member] Successor [Member]
Change in benefit obligation [Abstract]
Benefit Obligation	$ 141	$ 135	$ 110	$ 84	$ 141	$ 228	$ 225	$ 194	$ 243	$ 228
Service Cost	1	3	3	1		1	4	3	3
Interest Cost	1	6	6	2		2	10	10	7
Amendments	0	0		17		0	0		0
Benefits Paid, net	(1)	(2)		(3)		(3)	(11)		(9)
Curtailments	0	0		(80)		0	0		0
Actuarial Loss and other	5	18		6		3	28		14
Change in plan assets: [Abstract]
Fair Value of Plan Assets	119	110	102	129	119	144	133	127	155	144
Return on Plan Assets and other	8	0		4		11	0		6
Employer Contributions	2	10		9		3	17		14
Defined Benefit Plan, Funded Status of Plan	(22)	(25)		45		(84)	(92)		(88)
Amounts recognized in the consolidated balance sheets: [Abstract]
Noncurrent assets	6	4		57		0	0		0
Noncurrent Liabilities	(28)	(29)		(12)		(84)	(92)		(88)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	22	25		(45)		84	92		88
Amounts recognized in accumulated other comprehensive loss (pre-tax basis): [Abstract]
Net actuarial loss	23	25		2		74	83		17
Prior Service Cost	3	3		16		2	2		0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	$ 26	$ 28		$ 18		$ 76	$ 85		$ 17