Fair Value Measurements (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets transferred between Level 1 and Level 2	$ 0
Adjustments to acquisition related contingent consideration liability	45,000,000
Increase in fair value of contingent consideration due to 5% increase in projections	24,000,000
Decrease in fair value of contingent consideration due to 5% decrease in projections	37,000,000
Equity Method Investments	$ 347,000,000	$ 388,000,000
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)	2 years	2 years
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenue target period (in years)	4 years	4 years
Private Equity Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Method Investments	$ 76,000,000	$ 61,000,000