Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2011 interest_rate_swap	Feb. 28, 2011 interest_rate_swap	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Maximum [Member]	Mar. 31, 2014 Senior Debt Obligations Due 2014 [Member]	Feb. 28, 2011 Senior Debt Obligations Due 2014 [Member]	Mar. 31, 2014 Interest Rate Swap [Member]	Mar. 31, 2014 Private Equity Funds [Member]	Dec. 31, 2013 Private Equity Funds [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	$ 250,000,000
Number of interest rate swaps to convert fixed interest rate on notes to floating rate		2	2
Revenue target period (in years)				2 years	4 years
Adjustments to acquisition related contingent consideration liability	4,000,000
Increase in fair value of contingent consideration due to 5% increase in projections	17,000,000
Decrease in fair value of contingent consideration due to 5% decrease in projections	19,000,000
Long-term investments, cost basis									$ 13,000,000	$ 14,000,000