Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	18 Months Ended	3 Months Ended				9 Months Ended		12 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013 Restricted Shares	Sep. 30, 2013 Restricted Shares	Jun. 30, 2013 Restricted Shares	Sep. 30, 2013 Stock Options	Jun. 30, 2013 Stock Options	Mar. 31, 2013 Stock Options	Sep. 30, 2012 Stock Options	Sep. 30, 2013 Stock Options	Sep. 30, 2012 Stock Options	Dec. 31, 2012 Stock Options	Sep. 30, 2013 2009 Employee Option Plan	Sep. 30, 2013 2000 Employee Option Plan and 2009 Employee Option Plan	Sep. 30, 2013 2004 Directors Option Plan	Sep. 30, 2013 2012 Directors Restricted Stock Plan	Sep. 30, 2013 2000 Employee Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of additional stock options that can be granted																			0
Shares available for the granting of additional stock options															2,315,070		70,000	95,131
Options ratable vesting period																5 years	3 years
Options exercisable period																10 years	10 years
Number of additional stock options expected to be granted																	0
Expense incurred for stock-based compensation plans (in dollars)	$ 9,413	$ 8,066	$ 26,584	$ 23,167
Expense incurred for stock-based compensation plans, net of tax (in dollars)	6,940	5,885	19,432	16,542
Stock option activity
Options outstanding at the beginning of the period (in shares)								14,198,590	12,344,775	13,446,719		13,446,719
Options granted (in shares)								40,850	2,742,150
Options exercised (in shares)								(378,310)	(843,615)	(1,043,444)
Options forfeited (in shares)								(26,980)	(44,720)	(58,500)
Options outstanding at the end of the period (in shares)								13,834,150	14,198,590	12,344,775		13,834,150		13,446,719
Vested and non-vested expected to vest at the end of the period (in shares)								12,497,070				12,497,070
Exercisable at the end of the period (in shares)								5,768,549				5,768,549
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)								$ 51.23	$ 44.37	$ 43.39		$ 43.39
Weighted average exercise price, options granted (in dollars per share)								$ 76.77	$ 78.00
Weighted average exercise price, options exercised (in dollars per share)								$ 39.63	$ 38.03	$ 31.30
Weighted average exercise price, options forfeited (in dollars per share)								$ 57.17	$ 48.69	$ 50.58
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)								$ 51.61	$ 51.23	$ 44.37		$ 51.61		$ 43.39
Weighted average exercise price, vested and non-vested expected to vest (in dollars per share)								$ 51.02				$ 51.02
Weighted average exercise price, exercisable (in dollars per share)								$ 41.28				$ 41.28
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding								7 years 3 months 14 days	7 years 5 months 26 days	7 years 22 days				7 years 29 days
Weighted average remaining contractual term of options vested and non-vested expected to vest								7 years 2 months 12 days
Weighted average remaining contractual term of options exercisable								5 years 9 months 18 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)								358,182	379,390	373,596		358,182		268,596
Aggregate intrinsic value of options, vested and non-vested expected to vest (in dollars)								330,899				330,899
Aggregate intrinsic value of options exercisable (in dollars)								208,247				208,247
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares)								8,054,931	7,884,057	7,951,177		7,951,177
Non-vested options, options granted (in shares)								40,850	2,742,150
Non-vested options, options vested (in shares)								(3,200)	(2,526,556)	(8,620)
Non-vested options, options forfeited (in shares)								(26,980)	(44,720)	(58,500)
Non-vested options at the end of the period (in shares)								8,065,601	8,054,931	7,884,057		8,065,601		7,951,177
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)								$ 14.75	$ 13.35	$ 13.36		$ 13.36
Weighted average fair value at grant date, options granted (in dollars per share)								$ 17.97	$ 17.41
Weighted average fair value at grant date, options vested (in dollars per share)								$ 14.97	$ 13.32	$ 15.62
Weighted average fair value at grant date, options forfeited (in dollars per share)								$ 14.24	$ 13.40	$ 13.50
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)								$ 14.76	$ 14.75	$ 13.35		$ 14.76		$ 13.36
Total intrinsic value of stock options exercised (in dollars)								16,456			36,383	91,091	77,320
Total fair value of stock options vested (in dollars)								49			41	33,830	30,922
Total compensation cost related to non-vested options not yet recognized (in dollars)								92,718				92,718
Weighted average expected amortization period						7 months 24 days						3 years 6 months 7 days
Number of restricted shares issued					12,824		17,045
Weighted-average grant date fair value of restricted shares (in dollars per share)					$ 78.00		$ 53.78
Total compensation cost related to non-vested restricted shares not yet recognized (in dollars)						$ 645