Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jan. 16, 2015
Shares repurchase and retirement [Line Items]
Allocated Share-based Compensation Expense	$ 5,200	$ 4,100	$ 9,200	$ 7,300
Share repurchase program, amount authorized					$ 100,000
Stock Repurchased and Retired During Period, Shares			43,000
Stock Repurchased and Retired During Period, Value			$ 1,600
Stock Issued During Period, Shares, Acquisitions			794,700
Stock Issued During Period, Value, Acquisitions			$ 30,200
Additional Paid-in Capital [Member]
Shares repurchase and retirement [Line Items]
Stock Repurchased and Retired During Period, Value			400
Retained Earnings [Member]
Shares repurchase and retirement [Line Items]
Stock Repurchased and Retired During Period, Value			$ 1,200