Compensation Plans (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
RSUs, PSUs, and Director's Shares [Abstract]
Stock-based compensation expense				$ 25,495,000		$ 21,731,000
Cash Bonus Plan [Member]
Compensation plans
Accrued Cash Bonus Plan Expense	5,800,000		4,300,000	16,700,000		13,600,000
Restricted Stock Units (RSUs) [Member]
RSUs, PSUs, and Director's Shares [Abstract]
Number of Common Shares to be Received Upon Settlement				1
Stock-based compensation expense	3,700,000		3,900,000	10,000,000		6,500,000
Unrecognized stock based compensation expense	22,700,000			22,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value				19,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period, Net of Shares Withheld for Tax				138,807
Shares Paid for Tax Withholding for Share Based Compensation				67,702
Activity
Non-vested at the beginning of the period (in shares)				496,244
Granted (in shares)				329,939
Vested (in shares)				(206,509)
Forfeited (in shares)				(29,487)
Non-vested at the ending of the period (in shares)	590,187			590,187
Weighted Average Grant Date Fair Value
Non-vested outstanding at the beginning of the period (in dollars per share)				$ 51.81
Granted (in dollars per share)				$ 60.01
Vested (in dollars per share)				$ 49.73
Forfeited (in dollars per share)				$ 54.02
Non-vested outstanding at the ending of the period (in dollars per share)	$ 57.02			$ 57.02
Performance Shares [Member]
Compensation plans
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Multiplier Assumed				1
Share-based Compensation, Awards Other Than Options, Performance Measurement Period				3
RSUs, PSUs, and Director's Shares [Abstract]
Stock-based compensation expense	3,500,000		5,100,000	13,200,000
Unrecognized stock based compensation expense	22,700,000			22,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value				17,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period, Net of Shares Withheld for Tax				387,461
Shares Paid for Tax Withholding for Share Based Compensation				200,050
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Low End of Range				0
Common stock awards vesting multiplier, high end of range				2
Multiplier Applied to PSU Awards at Settlement				1.725
Activity
Non-vested at the beginning of the period (in shares)				669,308	[1]
Granted (in shares)				274,831	[1]
Vested (in shares)				(343,307)	[1]
Forfeited (in shares)				(22,371)	[1]
Non-vested at the ending of the period (in shares)	578,461	[1]		578,461	[1]
Weighted Average Grant Date Fair Value
Non-vested outstanding at the beginning of the period (in dollars per share)				$ 63.91
Granted (in dollars per share)				$ 64.13
Vested (in dollars per share)				$ 59.99
Forfeited (in dollars per share)				$ 69.50
Non-vested outstanding at the ending of the period (in dollars per share)			$ 66.13			$ 66.13
Employee Stock Option [Member]
Stock option activity
Stock options outstanding at the beginning of the year (in shares)				267,846
Exercised				(177,995)
Forfeited				0
Stock options vested and exercisable at the end of the period (in shares)	89,851			89,851
Weighted-Average Exercise Price
Stock options outstanding at the beginning of the period (in dollars per share)				$ 14.95
Exercised (in dollars per share)				$ 13.89
Forfeited (in dollars per share)
Stock options outstanding at the end of the period (in dollars per share)	$ 17.01			$ 17.01
Stock options vested and exercisable at the end of the period (in dollars per share)	$ 17.01			$ 17.01
Aggregate Intrinsic Value
Outstanding at the beginning of the period				9,983,000
Exercised				8,753,000
Outstanding at the end of the period	5,407,000			5,407,000
Vested at the end of the period	5,407,000			5,407,000
Shares Issued to the Board of Directors [Member]
Compensation plans
Stock Issued During Period, Shares, Share-based Compensation, Gross				28,169		30,486
RSUs, PSUs, and Director's Shares [Abstract]
Stock-based compensation expense			147,000	1,400,000		1,300,000
Employee Stock [Member]
Employee Stock Purchase Program
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	15.00%			15.00%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription	$ 25,000			$ 25,000
ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfOfferingDatePricePaid				85.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,300,000			1,300,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans				44,437		37,124

[1] (1) The number of awards assumes a one multiplier. The final number of shares of common stock issued may vary depending on the three-year performance multiplier, which ranges from zero to two.