Investments in Unconsolidated Subsidiaries - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended					3 Months Ended		0 Months Ended				12 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013 Equity Method Investments [Member]	Dec. 31, 2013 Equity Method Investment Goodwill [Member]	Dec. 31, 2013 Megapolis [Member]	Dec. 12, 2013 Megapolis [Member]	Sep. 30, 2013 AITA [Member]	Mar. 31, 2014 STAEM [Member]	Mar. 31, 2014 Other Affiliates [Member]	Dec. 31, 2013 Other Affiliates [Member]	Dec. 31, 2013 Minimum [Member] Equity Method Investments [Member]	Mar. 31, 2014 Minimum [Member] Other Affiliates [Member]	Dec. 31, 2013 Maximum [Member] Equity Method Investments [Member]	Mar. 31, 2014 Maximum [Member] Other Affiliates [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated subsidiaries		$ 1,536	$ 1,460		$ 519					$ 35	$ 42
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity				579
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity, Amortization Period												4 years		20 years
Proceeds from Equity Method Investment, Dividends or Distributions	13	1
Equity Method Investment, Ownership Percentage							20.00%	49.00%	25.00%				40.00%		50.00%
Purchase Price of Equity Method Investments						750		625
Contingent Consideration Equity Method Investment						100
Contingent Consideration Measurement Period						4 years
Investments In Unconsolidated Subsidiaries Notes Receivable						100
Equity Method Investments Discounted Liability						$ 86