Other Liabilities Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Property	Dec. 31, 2009 Property	Mar. 31, 2013	Dec. 31, 2012
Other Liabilities [Line Items]
Other Liabilities, Current			$ 3,288	$ 3,741
Other Liabilities, Noncurrent			1,132	1,176
Number Of Real Estate Assets Financed		111
Operating Leases, Income Statement, Minimum Lease Revenue		145
Lease Agreement Contractual Term		40 years
Capital Leases, Future Minimum Payments Receivable		54
Number Of Real Estate Surface Assets Repurchased	1
Mortgage Term			5 years
Debt Instrument, Basis Points			275
Minimum
Other Liabilities [Line Items]
Capital Leases, Future Minimum Payments Receivable		15
Maximum
Other Liabilities [Line Items]
Capital Leases, Future Minimum Payments Receivable		27
Chk Utica [Member]
Other Liabilities [Line Items]
Other Liabilities, Current			20	18
Other Liabilities, Noncurrent			289	293
Chk C T [Member]
Other Liabilities [Line Items]
Other Liabilities, Current			13	14
Other Liabilities, Noncurrent			$ 173	$ 178