Subsequent Events Subsequent Events - Narrative (Details) $ in Millions		3 Months Ended
	May. 04, 2016 USD ($) a	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Subsequent Event [Line Items]
Proceeds from divestitures of proved and unproved properties		$ 62	$ 21
STACK Play [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Net Acres | a	42,000
Proceeds from divestitures of proved and unproved properties	$ 470