Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended					1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Assets Held under Capital Leases	Dec. 31, 2012 Assets Held under Capital Leases	Dec. 31, 2012 Corporate Headquarters Land and Buildings	Dec. 31, 2012 Corporate Headquarters Building Property	Dec. 31, 2012 Corporate Headquarters Land Property
Significant Acquisitions and Disposals [Line Items]
Payment to acquire property and equipment	$ 3,444,000,000	$ 3,785,000,000	$ 1,811,000,000			$ 1,200,000,000		$ 210,000,000
Number of property and equipment acquired							11	3
Property and equipment, estimated useful lives							40 years
Depreciation expense on fixed assets including amortization	2,460,000,000	1,653,000,000	1,034,000,000
Amortization of fixed assets acquired under capital lease obligations	826,000,000	510,000,000	335,000,000
Gross assets remaining under leases				4,200,000,000	2,300,000,000
Accumulated depreciation associated with leases				1,900,000,000	1,100,000,000
Cash paid for interest on capital leases	41,000,000	51,000,000	44,000,000
Gross finance leased assets	578,000,000	9,000,000
Finance leased assets, accumulated depreciation	$ 22,000,000	$ 5,000,000