Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Unrecognized tax benefits accrued interest	$ 821,000	$ 555,000
Tax benefits associated with the exercise, vesting or disposition of stock under stock plans recognized as an adjustment of additional paid-in capital	10,800,000	7,400,000	1,500,000
Income taxes paid	$ 128,800,000	$ 97,100,000	$ 63,400,000