Debt - Narrative (Details)													3 Months Ended
	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2015 Secured Debt [Member] USD ($)	Feb. 28, 2015 European Medium Term Notes [Member] Euro Medium Due February 2018 [Member] EUR (€)	Apr. 23, 2015 Subsequent Event [Member] Senior Notes [Member] Floating Rate Senior Notes Due April Two Thousand Eighteen [Member] USD ($)	Jan. 31, 2015 Parent Company [Member] Senior Notes [Member] USD ($)	Jan. 31, 2015 Parent Company [Member] Senior Notes [Member] Senior Notes Due January 2020 [Member] USD ($)	Jan. 31, 2015 Parent Company [Member] Senior Notes [Member] Senior Notes Due January 2025 [Member] USD ($)	Jan. 31, 2015 Parent Company [Member] Senior Notes [Member] Floating Rate Senior Notes Due January 2020 [Member] London Interbank Offered Rate (LIBOR) [Member] USD ($)	Apr. 23, 2015 Parent Company [Member] Subsequent Event [Member] Senior Notes [Member] USD ($)	Apr. 23, 2015 Parent Company [Member] Subsequent Event [Member] Senior Notes [Member] Senior Notes Due April 2018 [Member] USD ($)	Apr. 23, 2015 Parent Company [Member] Subsequent Event [Member] Senior Notes [Member] Senior Notes Due 2022 [Member] USD ($)	Mar. 31, 2015 Revolving Credit Facility [Member] Unsecured Debt [Member] International Segment [Member] USD ($)	Mar. 31, 2015 Revolving Credit Facility [Member] Secured Debt [Member] USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount	$ 11,300,000,000	$ 8,400,000,000	$ 2,000,000,000	€ 650,000,000	$ 300,000,000	$ 2,250,000,000.00	$ 1,000,000,000.0	$ 1,000,000,000.0	$ 250,000,000	$ 2,400,000,000.0	$ 850,000,000	$ 1,250,000,000.00
Increase in Credit Facilities during period													$ 90,000,000	$ 770,000,000
Interest rate (percent)				0.85%			3.15%	4.00%			2.40%	3.45%