Other Liabilities Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2013 Property	Dec. 31, 2011 Property	Dec. 31, 2009 Property	Dec. 31, 2012
Other Liabilities [Line Items]
Other Liabilities, Current	$ 3,549			$ 3,741
Other Liabilities, Noncurrent	1,069			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	2	1
Mortgage Term			5 years
Debt Instrument, Basis Points			275
Chesapeake Utica L L C [Member]
Other Liabilities [Line Items]
Other Liabilities, Current	21			18
Other Liabilities, Noncurrent	287			293
Chesapeake Cleveland Tonkawa L.L.C
Other Liabilities [Line Items]
Other Liabilities, Current	11			14
Other Liabilities, Noncurrent	168			178
Minimum
Other Liabilities [Line Items]
Capital Leases, Future Minimum Payments Receivable			15
Maximum
Other Liabilities [Line Items]
Capital Leases, Future Minimum Payments Receivable			$ 27