Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
2009 Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for the granting of additional stock options	4,970,270
2000 Option Plan and 2009 Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Options ratable vesting period	5 years
Options exercisable period	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	3 years
Options exercisable period	10 years
Restricted Shares
Weighted Average Fair Value at Grant Date
Weighted average expected amortization period	4 months 20 days
Number of restricted shares issued	16,429
Weighted-average grant date fair value of restricted shares (in dollars per share)	$ 53.26
Total compensation cost related to non-vested restricted shares not yet recognized (in dollars)	$ 348
Restricted Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Number of restricted shares available for future grants under the Restricted Stock Plan	108,571
Stock Options
Stock option activity
Options outstanding at the beginning of the period (in shares)	14,016,900	12,706,324	12,704,303
Options granted (in shares)	2,990,000	2,551,350	2,602,500
Options exercised (in shares)	(3,252,961)	(1,037,674)	(2,331,429)
Options forfeited (in shares)	(307,220)	(203,100)	(269,050)
Options outstanding at the end of the period (in shares)	13,446,719	14,016,900	12,706,324	12,704,303
Vested and non-vested expected to vest at the end of the period (in shares)	12,329,575
Exercisable at the end of the period (in shares)	5,495,542
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)	$ 38.00	$ 33.93	$ 29.58
Weighted average exercise price, options granted (in dollars per share)	$ 53.31	$ 53.45	$ 43.00
Weighted average exercise price, options exercised (in dollars per share)	$ 29.33	$ 25.14	$ 19.99
Weighted average exercise price, options forfeited (in dollars per share)	$ 42.84	$ 39.75	$ 37.18
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)	$ 43.39	$ 38.00	$ 33.93	$ 29.58
Weighted average exercise price, vested and non-vested expected to vest (in dollars per share)	$ 43.01
Weighted average exercise price, exercisable (in dollars per share)	$ 37.02
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding	7 years 29 days	6 years 10 months 20 days	7 years 2 months 5 days	7 years 1 month 28 days
Weighted average remaining contractual term of options vested and non-vested expected to vest	6 years 11 months 23 days
Weighted average remaining contractual term of options exercisable	5 years 6 months 18 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)	286,596
Aggregate intrinsic value of options, vested and non-vested expected to vest (in dollars)	267,483
Aggregate intrinsic value of options exercisable (in dollars)	152,103
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 granted (in shares)	2,990,000
Non-vested options, options vested (in shares)	(2,368,179)
Non-vested options, options forfeited (in shares)	(307,220)
Non-vested options at the end of the period (in shares)	7,951,177	7,636,576
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 granted (in dollars per share)	$ 12.96	$ 14.19	$ 14.69
Weighted average fair value at grant date, options vested (in dollars per share)	$ 13.07
Weighted average fair value at grant date, options forfeited (in dollars per share)	$ 13.09
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)	$ 13.36	$ 13.41
Total intrinsic value of stock options exercised (in dollars)	95,891	29,697	67,841
Total fair value of stock options vested (in dollars)	30,964	28,563	23,714
Total compensation cost related to non-vested options not yet recognized (in dollars)	$ 75,901
Weighted average expected amortization period	3 years 2 months 26 days