Stock-based Compensation Stock-based Compensation (Details textual) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation [Abstract]
Unrecognized stock-based compensation costs, net of estimated forfeitures	$ 50,400,000		$ 50,400,000
Weighted average period of unrecognized stock-based compensation costs, net of estimated forfeitures	2 years 0 months
Cash received from the exercise of stock options	2,000,000	1,500,000	3,700,000	3,100,000
Related tax benefit realized from the exercise of the stock options	400,000	800,000	300,000	100,000
Statement [Line Items]
Proceeds from shares issued pursuant to stock-based compensation plans			5,953,000	7,117,000
Time-vested restricted stock unit [Member]
Statement [Line Items]
Restricted stock units granted			1,166,000	984,000
Weighted average grant date fair value per share			$ 23.96	$ 21.67
Market-based restricted stock unit
Statement [Line Items]
Restricted stock units granted			7,000	795,000
Weighted average grant date fair value per share			$ 15.87	$ 11.73
Vesting period for market-based RSUs			3 years
Employee Stock
Statement [Line Items]
Weighted average grant date fair value per share	$ 0.00	$ 0.00	$ 5.25	$ 5.02
Number of common stock shares issued			125,000
Shares of common stock reserved for future issuance under all of the stock incentive plans	3,728,000		3,728,000
Proceeds from shares issued pursuant to stock-based compensation plans			$ 2,100,000