Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011	Dec. 31, 2011 Y
Share-based Compensation Arrangement by Share-based Payment Award
Expense incurred for stock-based compensation plans (in dollars)	$ 7,491	$ 6,320
Expense incurred for stock-based compensation plans, net of tax (in dollars)	5,353	4,582
Stock option activity
Options outstanding at the beginning of the period (in shares)	14,016,900
Options exercised (in shares)	(853,460)
Options forfeited (in shares)	(123,000)
Options outstanding at the end of the period (in shares)	13,040,440
Vested and non-vested expected to vest at the end of the period (in shares)	12,218,010
Exercisable at the end of the period (in shares)	5,533,864
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)	$ 38.00
Weighted average exercise price, options exercised (in dollars per share)	$ 26.23
Weighted average exercise price, options forfeited (in dollars per share)	$ 38.53
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)	$ 38.77
Weighted average exercise price, vested and non-vested expected to vest (in dollars per share)	$ 38.37
Weighted average exercise price, exercisable (in dollars per share)	$ 32.32
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding (in years)	6.79		6.89
Weighted average remaining contractual term of options vested and non-vested expected to vest (in years)	6.69
Weighted average remaining contractual term of options exercisable (in years)	5.29
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)	273,830		125,067
Aggregate intrinsic value of options, vested and non-vested expected to vest (in dollars)	261,463
Aggregate intrinsic value of options exercisable (in dollars)	151,911
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares)	7,636,576
Non-vested options, options vested (in shares)	(7,000)
Non-vested options, options forfeited (in shares)	(123,000)
Non-vested options at the end of the period (in shares)	7,506,576
Weighted Average Fair Value at Grant Date
Weighted average fair value at the grant date, options outstanding at the beginning of the period (in dollars per share)	$ 13.41
Weighted average fair value at grant date, options vested (in dollars per share)	$ 16.98
Weighted average fair value at grant date, options forfeited (in dollars per share)	$ 12.52
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)	$ 13.43
Total intrinsic value of stock options exercised (in dollars)	24,819	19,663
Total fair value of stock options vested (in dollars)	119
Total compensation cost related to non-vested options not yet recognized (in dollars)	$ 66,949
Weighted average expected amortization period (in years)	3.08
2009 Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for the granting of additional stock options	7,788,950
2000 Option Plan and 2009 Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Options ratable vesting period (in years)	5 years
Options exercisable period (in years)	10 years
Directors Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for the granting of additional stock options	70,000
Options ratable vesting period (in years)	3 years
Options exercisable period (in years)	10 years