Fair Value Measurements (Narrative) (Details) (USD $)	9 Months Ended			9 Months Ended			9 Months Ended
	Sep. 30, 2014	Mar. 31, 2011 interest_rate_swap	Dec. 31, 2013 Private Equity Funds [Member]	Sep. 30, 2014 Minimum [Member]	Sep. 30, 2014 Maximum [Member]	Jun. 30, 2014 Senior Debt Obligations Due 2014 [Member]	Sep. 30, 2014 Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value interest rate swap discount rate							1.60%
Fair value interest rate swap derivatives						$ 250,000,000
Number of interest rate swaps to convert fixed interest rate on notes to floating rate		2
Revenue target period (in years)				2 years	4 years
Adjustments to acquisition related contingent consideration liability	17,000,000
Increase in fair value of contingent consideration due to 5% increase in projections	22,000,000
Decrease in fair value of contingent consideration due to 5% decrease in projections	25,000,000
Long-term investments, cost basis			$ 14,000,000