Subsequent Events Subsequent Events - Summary of Business Combination (Details) - CAC - Subsequent Event [Member] $ in Millions	Oct. 06, 2017 USD ($)
Subsequent Event [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 152	[1]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(96)
Business Combination, Elimination of Noncontrolling Interest in CGP	1,751	[1]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$ 1,807

[1] (1) Amount is reported net of CAC’s equity investment in CGP as this will be eliminated in consolidation.