Subsequent Events - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended					0 Months Ended			0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Drilling Rigs [Member]	Dec. 31, 2013 Compressor [Member]	Jan. 14, 2014 Sale of Chaparral Energy [Member] Chaparral Energy, Inc.	Jan. 21, 2014 Acquisition of Drilling Rigs [Member] Drilling Rigs [Member] Rigs	Jan. 21, 2014 Acquisition of Drilling Rigs [Member] Terminated Leases [Member] Drilling Rigs [Member]	Feb. 20, 2014 Acquisition of Compressors [Member] Compressor [Member] Compressor	Feb. 19, 2014 Acquisition of Compressors [Member] Compressor [Member]
Subsequent Event [Line Items]
Proceeds from sales of investments	$ 115	$ 2,000	$ 0			$ 215
Equipment, Number of Units							10		576
Operating Leases, Future Minimum Payments Due, Next Twelve Months	117			51	53			9		126
Payments to Acquire Property, Plant, and Equipment				$ 141			$ 31		$ 168