Fair Value Measurements - Additional Information (Details)	12 Months Ended								12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2013 Credit Agreement USD ($)	Dec. 31, 2012 Credit Agreement USD ($)	Dec. 31, 2013 Receivables securitization USD ($)	Dec. 31, 2012 Receivables securitization USD ($)	Dec. 31, 2013 Senior Notes USD ($)	Dec. 31, 2012 Senior Notes USD ($)	Dec. 31, 2013 ECP 2012 Contingent Payment USD ($)	Dec. 31, 2013 ECP 2012 Contingent Payment GBP (£)	Dec. 31, 2012 ECP 2012 Contingent Payment GBP (£)	Dec. 31, 2012 ECP 2013 Contingent Payment Draco Portion GBP (£)
Fair Value Measurements
Maximum payment under contingent consideration agreement											£ 25,000,000	£ 27,000,000
Losses related to contingent consideration obligations outstanding at period-end	3,000,000	2,600,000
Borrowings under credit agreement, carrying value			672,600,000	974,600,000
Borrowings under receivable securitization facility, carrying value					0	80,000,000
Contingent consideration payments	39,117,000	3,100,000							33,900,000	22,400,000
Contingent consideration other settlements									3,900,000	2,600,000
Debt instrument, fair value							561,000,000
Debt instrument, face amount							$ 600,000,000	$ 0