Stock-Based Compensation - CEC Stock Option Grants and Exercises (Details) - Parent [Member] - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted		1,844,332	1,500,770	550,812
Weighted Average Grant-Date Fair Value per share (1)	[1]	$ 3.38	$ 10.27	$ 5.95
Weighted Average Exercise Price per Share (1)	[1]	$ 10.04	$ 21.18	$ 13.65
Number of options exercised		58,700	317,703	143,109
Cash received for options exercised	[2]	$ 0	$ 3	$ 1
Aggregate intrinsic value of options exercised (2)	[2]	$ 0	$ 2	$ 2

[1] Represents the weighted-average grant date fair value per option, using the Monte Carlo simulation option-pricing model for performance-based options, and the Black-Scholes option-pricing model for time-based options.

[2] 2015 amounts are immaterial.