Fair Values of Certain Financial Assets and Liabilities and Other Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 23, 2012	Dec. 31, 2011
Carrying (Reported) Amount, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Collateralized Mortgage Backed Securities
Financial assets
Financial assets	$ 68	$ 65
Carrying (Reported) Amount, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Credit Facility
Financial liabilities
Financial liabilities	141	117
Carrying (Reported) Amount, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Mortgage Backed Securities, Other
Financial liabilities
Financial liabilities	1,096	1,091
Carrying (Reported) Amount, Fair Value Disclosure | Quoted Prices in Active Markets for Identical Assets (Level 1) | Senior Notes
Financial liabilities
Financial liabilities	3,992	3,641
Carrying (Reported) Amount, Fair Value Disclosure | Quoted Prices in Active Markets for Identical Assets (Level 1) | Exchangeable Debentures
Financial liabilities
Financial liabilities	907	902
Portion at Fair Value, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Collateralized Mortgage Backed Securities
Financial assets
Financial assets	79	76
Portion at Fair Value, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Credit Facility
Financial liabilities
Financial liabilities	141	117
Portion at Fair Value, Fair Value Disclosure | Significant Other Observable Inputs (Level 2) | Mortgage Backed Securities, Other
Financial liabilities
Financial liabilities	1,117	1,114
Portion at Fair Value, Fair Value Disclosure | Quoted Prices in Active Markets for Identical Assets (Level 1) | Senior Notes
Financial liabilities
Financial liabilities	4,177	3,772
Portion at Fair Value, Fair Value Disclosure | Quoted Prices in Active Markets for Identical Assets (Level 1) | Exchangeable Debentures
Financial liabilities
Financial liabilities	$ 1,120	$ 1,076