Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended	3 Months Ended		6 Months Ended						6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Stock Options	Mar. 31, 2014 Stock Options	Jun. 30, 2013 Stock Options	Jun. 30, 2014 Stock Options	Jun. 30, 2013 Stock Options	Dec. 31, 2013 Stock Options	Jun. 30, 2014 Restricted Shares	Jun. 30, 2013 Restricted Shares	Jun. 30, 2014 Restricted Shares	Jun. 30, 2013 Restricted Shares	Jun. 30, 2014 2000 Employee Option Plan	Jun. 30, 2014 2009 Employee Option Plan	May 31, 2014 2009 Employee Option Plan	Apr. 30, 2014 2009 Employee Option Plan	Jun. 30, 2014 2000 Employee Option Plan and 2009 Employee Option Plan	Jun. 30, 2014 2004 Directors Option Plan	Jun. 30, 2014 2012 Directors Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of additional stock options that can be granted (in shares)															0
Common Stock reserved for issuance																	29,000,000	16,000,000
Shares available for the granting of additional stock options																12,401,170				70,000	85,961
Options ratable vesting period																			5 years	3 years
Options exercisable period																			10 years	10 years
Number of additional stock options expected to be granted (in shares)																				0
Expense incurred for stock-based compensation plans (in dollars)	$ 9,973	$ 8,890	$ 19,249	$ 17,175
Expense incurred for stock-based compensation plans, net of tax (in dollars)	7,333	6,473	14,137	12,503
Stock option activity
Options outstanding at the beginning of the period (in shares)					13,088,300	13,422,226		13,422,226
Options granted (in shares)					3,023,500	32,500
Options exercised (in shares)					(1,128,975)	(314,966)
Options forfeited (in shares)					(49,560)	(51,460)
Options outstanding at the end of the period (in shares)					14,933,265	13,088,300		14,933,265		13,422,226
Vested and non-vested options expected to vest at the end of the period (in shares)					13,478,241			13,478,241
Exercisable at the end of the period (in shares)					6,616,375			6,616,375
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)					$ 52.14	$ 51.80		$ 51.80
Weighted average exercise price, options granted (in dollars per share)					$ 95.44	$ 89.13
Weighted average exercise price, options exercised (in dollars per share)					$ 39.80	$ 40.41
Weighted average exercise price, options forfeited (in dollars per share)					$ 65.22	$ 59.80
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)					$ 61.79	$ 52.14		$ 61.79		$ 51.80
Weighted average exercise price, vested and non-vested options expected to vest (in dollars per share)					$ 60.92			$ 60.92
Weighted average exercise price, exercisable (in dollars per share)					$ 45.58			$ 45.58
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding					7 years 5 months 16 days	6 years 10 months 20 days				7 years 29 days
Weighted average remaining contractual term of options vested options and non-vested expected to vest					7 years 4 months 13 days
Weighted average remaining contractual term of options exercisable					5 years 11 months 5 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)					515,908	517,164		515,908		501,706
Aggregate intrinsic value of options, vested and non-vested options expected to vest (in dollars)					477,353			477,353
Aggregate intrinsic value of options exercisable (in dollars)					335,874			335,874
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares)					7,990,961	8,016,921		8,016,921
Non-vested options, options granted (in shares)					3,023,500	32,500
Non-vested options, options vested (in shares)					(2,648,011)	(7,000)
Non-vested options, options forfeited (in shares)					(49,560)	(51,460)
Non-vested options at the end of the period (in shares)					8,316,890	7,990,961		8,316,890		8,016,921
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)					$ 14.79	$ 14.77		$ 14.77
Weighted average fair value at grant date, options granted (in dollars per share)					$ 17.23	$ 21.23
Weighted average fair value at grant date, options vested (in dollars per share)					$ 13.95	$ 16.98
Weighted average fair value at grant date, options forfeited (in dollars per share)					$ 15.31	$ 14.82
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)					$ 15.94	$ 14.79		$ 15.94		$ 14.77
Total intrinsic value of stock options exercised (in dollars)					62,893		34,093	78,453	74,635
Total fair value of stock options vested (in dollars)					36,939		33,647	37,058	33,781
Total compensation cost related to non-vested options not yet recognized (in dollars)					112,848			112,848
Weighted average expected amortization period								3 years 9 months 11 days					10 months 24 days
Number of restricted shares issued											9,170	12,824		17,045
Weighted-average grant date fair value of restricted shares (in dollars per share)											$ 95.43	$ 78.00		$ 53.78
Total compensation cost related to non-vested restricted shares not yet recognized (in dollars)											$ 781		$ 781