Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Long-term Debt, Fair Value	$ 990us-gaap_LongTermDebtFairValue	$ 1,002us-gaap_LongTermDebtFairValue
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000us-gaap_PreferredStockSharesAuthorized	50,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common Class A
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common stock, shares issued	104,505,449	104,421,488
Common stock, shares outstanding	104,505,449	104,421,488
Common Class B
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	9,873,972	9,876,178
Common stock, shares outstanding	9,873,972	9,876,178
Common Class C
Common stock, par or stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common stock, shares issued	228,781,948	228,595,332
Common stock, shares outstanding	228,781,948	228,595,332

Face amount or stated value per share of common stock.

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