Supplemental Cash Flows Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flows Information [Abstract]
Cash paid for income taxes	$ 49,500,000	$ 28,300,000	$ 20,400,000
Capital Expenditures Incurred but Not yet Paid	600,000	900,000	600,000
Tax Benefit from Stock Options Exercised	10,200,000	7,100,000	3,300,000
Interest Paid	26,600,000	21,100,000	400,000
Business Combination, Contingent Consideration, Liability	45,300,000	7,000,000	2,500,000
Loss on extinguishment of debt and related interest expense	$ 0	$ 14,437,000	$ 0