Debt (Schedule of Balances Available for Borrowings)(Details) - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
		Sep. 30, 2015		Dec. 31, 2014	Sep. 30, 2014
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowings outstanding	[2]	$ 345	[1]	$ 0
Letters of credit issued		0
Available for borrowing		555
Maximum borrowing base		900			$ 900
Proceeds from lines of credit		475
Repayments of lines of credit		130
Accounts Receivable Securitization Facility [Member]
Debt Instrument [Line Items]
Borrowings outstanding	[4]	30	[3]	$ 35
Letters of credit issued		74
Available for borrowing		5
Total borrowing base		109
Maximum borrowing base	[5]	135
Repayments of lines of credit		15
Outstanding accounts receivable transferred by the Originators to the Transferor		$ 152
Series A common stock, $0.0001 par value, 400,000,000 shares authorized (2015: 166,620,081 issued and 146,703,591 outstanding; 2014: 166,169,335 issued and 152,902,710 outstanding)
Debt Instrument [Line Items]
Common stock, par value		$ 0.0001		$ 0.0001

[1] The Company borrowed $475 million and repaid $130 million during the nine months ended September 30, 2015. Borrowings were primarily used to fund repurchases of the Company's Series A common stock, par value $0.0001 per share ("Common Stock").

[2] The weighted average interest rate was 1.7% and 0.0% as of September 30, 2015 and December 31, 2014, respectively.

[3] The Company repaid $15 million of borrowings outstanding during the nine months ended September 30, 2015.

[4] The weighted average interest rate was 0.7% as of September 30, 2015 and December 31, 2014.

[5] Outstanding accounts receivable transferred by the Originators to the Transferor was $152 million.