Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			15 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Restricted Shares	Mar. 31, 2013 Restricted Shares	Jun. 30, 2013 Stock Options	Mar. 31, 2013 Stock Options	Jun. 30, 2012 Stock Options	Jun. 30, 2013 Stock Options	Jun. 30, 2012 Stock Options	Dec. 31, 2012 Stock Options	Jun. 30, 2013 2009 Option Plan	Jun. 30, 2013 2000 Option Plan and 2009 Option Plan	Jun. 30, 2013 Directors Option Plan	Jun. 30, 2013 Directors Restricted Stock Plan	Jun. 30, 2013 2000 Option Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of additional options that can be granted																	0
Shares available for the granting of additional stock options													2,328,940		70,000	95,131
Options ratable vesting period														5 years	3 years
Options exercisable period														10 years	10 years
Number of additional options expected to be granted															0
Expense incurred for stock-based compensation plans (in dollars)	$ 8,890	$ 7,610	$ 17,175	$ 15,101
Expense incurred for stock-based compensation plans, net of tax (in dollars)	6,473	5,498	12,503	10,851
Stock option activity
Options outstanding at the beginning of the period (in shares)							12,344,775	13,446,719		13,446,719
Options granted (in shares)							2,742,150
Options exercised (in shares)							(843,615)	(1,043,444)
Options forfeited (in shares)							(44,720)	(58,500)
Options outstanding at the end of the period (in shares)							14,198,590	12,344,775		14,198,590		13,446,719
Vested and non-vested expected to vest at the end of the period (in shares)							12,806,480			12,806,480
Exercisable at the end of the period (in shares)							6,143,659			6,143,659
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)							$ 44.37	$ 43.39		$ 43.39
Weighted average exercise price, options granted (in dollars per share)							$ 78.00
Weighted average exercise price, options exercised (in dollars per share)							$ 38.03	$ 31.30
Weighted average exercise price, options forfeited (in dollars per share)							$ 48.69	$ 50.58
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)							$ 51.23	$ 44.37		$ 51.23		$ 43.39
Weighted average exercise price, vested and non-vested expected to vest (in dollars per share)							$ 50.64			$ 50.64
Weighted average exercise price, exercisable (in dollars per share)							$ 41.17			$ 41.17
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding							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 4 months 24 days
Weighted average remaining contractual term of options exercisable							6 years 14 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)							379,390	373,596		379,390		268,596
Aggregate intrinsic value of options, vested and non-vested expected to vest (in dollars)							349,739			349,739
Aggregate intrinsic value of options exercisable (in dollars)							225,898			225,898
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares)							7,884,057	7,951,177		7,951,177
Non-vested options, options granted (in shares)							2,742,150
Non-vested options, options vested (in shares)							(2,526,556)	(8,620)
Non-vested options, options forfeited (in shares)							(44,720)	(58,500)
Non-vested options at the end of the period (in shares)							8,054,931	7,884,057		8,054,931		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)							$ 13.35	$ 13.36		$ 13.36
Weighted average fair value at grant date, options granted (in dollars per share)							$ 17.41
Weighted average fair value at grant date, options vested (in dollars per share)							$ 13.32	$ 15.62
Weighted average fair value at grant date, options forfeited (in dollars per share)							$ 13.40	$ 13.50
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)							$ 14.75	$ 13.35		$ 14.75		$ 13.36
Total intrinsic value of stock options exercised (in dollars)							34,093		16,118	74,635	40,937
Total fair value of stock options vested (in dollars)							33,647		30,763	33,781	30,882
Total compensation cost related to non-vested options not yet recognized (in dollars)							100,520			100,520
Weighted average expected amortization period					10 months 24 days					3 years 8 months 12 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)					$ 896