General - Basis of Presentation (Details 2) (USD $)	1 Months Ended	9 Months Ended		9 Months Ended				9 Months Ended
	Jun. 30, 2011	Sep. 30, 2012 Long-Term Incentive Plan	Sep. 30, 2012 Long-Term Incentive Plan Deferred stock units	Sep. 30, 2012 Long-Term Incentive Plan Stock options Y installment	Sep. 30, 2011 Long-Term Incentive Plan Stock options Y	Sep. 30, 2012 Long-Term Incentive Plan Stock, restricted stock awards and restricted stock units	Dec. 31, 2011 Long-Term Incentive Plan Stock, restricted stock awards and restricted stock units	Sep. 30, 2012 Long-Term Incentive Plan Restricted stock awards Y
Details of stock benefit plans
Increased in number of shares available for issuance		4,400,000
Number of shares of common stock that may be issued under the Plan		9,666,666
Maximum number of shares of common stock authorized to be issued under the Plan		14,066,666
Stock split ratio	2
Dividend in form of number of shares for each outstanding share of common stock	1
Options to purchase common stock outstanding (in shares)				5,202,000
Shares outstanding under the plan			2,000			1,772,000	548,000
Shares available for future grant		3,104,000
Number of equal annual installments over which options outstanding are cumulatively exercisable				4
Stock-based compensation additional disclosures
Weighted average grant date fair value of options granted (in dollars per share)				$ 16.13	$ 13.82
Total intrinsic value of options exercised (in dollars)				$ 50,900,000	$ 5,000,000
Fair value of options vested during the period (in dollars)				15,200,000	9,900,000
Unrecognized compensation expense (in dollars)				29,700,000				13,400,000
Weighted-average period over which unrecognized compensation cost is expected to be recognized (in years)				3.1				0.7
Cash received from the exercise of stock option				29,900,000	6,100,000
Options exercisable commencement period from grant date (in years)				1
Term over which options are granted				P10Y
Post-vesting cancellation rate used in valuation of options (as a percent)				0.00%
Weighted-average assumptions used to estimate the fair value of stock options granted
Risk-free interest rate (as a percent)				1.08%	1.64%
Expected term (in years)				6.25	6.25
Expected volatility (as a percent)				44.15%	43.69%
Expected dividend yield (as a percent)				3.61%	0.66%
Shares
Options outstanding at the beginning of the period (in shares)				5,732,000
Granted (in shares)				1,292,000
Exercised (in shares)				(1,506,000)
Forfeited (in shares)				(314,000)
Expired (in shares)				(2,000)
Options outstanding at the end of the period (in shares)				5,202,000
Vested and expected to vest (in shares)				5,041,000
Options exercisable (in shares)				802,000
Weighted Avg. Exercise Price (in dollars per share)
Options outstanding at the beginning of the period (in dollars per share)				$ 21.99
Granted (in dollars per share)				$ 51.04
Exercised (in dollars per share)				$ 19.86
Forfeited (in dollars per share)				$ 28.42
Expired (in dollars per share)				$ 31.31
Options outstanding at the end of the period (in dollars per share)				$ 29.43
Vested and expected to vest (in dollars per share)				$ 29.32
Options exercisable (in dollars per share)				$ 23.20
Weighted Avg. Remaining Contractual Term
Options outstanding at the end of the period (in years)				8.51
Vested and expected to vest (in years)				8.50
Options exercisable (in years)				8.15
Aggregate Intrinsic Value (in dollars)
Options outstanding at the end of the period (in dollars)				152,787,000
Vested and expected to vest (in dollars)				148,596,000
Options exercisable (in dollars)				$ 28,555,000