Fair Value Measurements (Narrative) (Details) (USD $)	12 Months Ended					12 Months Ended
	Dec. 31, 2013	Mar. 31, 2011 interest_rate_swap	Feb. 28, 2011 interest_rate_swap	Dec. 31, 2013 Senior Debt Obligations Due 2014 [Member]	Feb. 28, 2011 Senior Debt Obligations Due 2014 [Member]	Dec. 31, 2013 Interest Rate Swap [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2013 Private Equity Funds [Member]	Dec. 31, 2012 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 measurement on senior notes subject to interest rate swaps				$ 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	2 years	4 years	4 years
Assets transferred between Level 1 and Level 2	0
Assets transferred between Level 2 To Level 3	0
Adjustments to acquisition related contingent consideration liability	32,000,000
Increase in fair value of contingent consideration due to 5% increase in projections	8,000,000
Decrease in fair value of contingent consideration due to 5% decrease in projections	9,000,000
Long-term Investments											$ 14,000,000	$ 16,000,000