General - Stock Compensation (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) company $ / shares shares	Jun. 30, 2015 USD ($)
Share-based compensation
Stock compensation expense | $	$ 9,510,000	$ 13,795,000	$ 18,397,000	$ 27,696,000
Tax benefit from exercise of stock options and vesting of stock awards | $			472,000	3,774,000
Change to additional paid in capital related to tax net benefits (deficiencies) | $			300,000	3,700,000
Excess tax benefits of tax deductions in recognized stock compensation expenses | $			500,000	3,800,000
Tax deficiencies and adjustments from exercise of stock options and vesting of stock awards | $			$ (200,000)	$ (100,000)
Minimum
Stock options, Non vested restricted stock awards and nonvested restricted stock units
Estimated forfeitures (as a percent)			0.00%	0.00%
Maximum
Stock options, Non vested restricted stock awards and nonvested restricted stock units
Estimated forfeitures (as a percent)			4.00%	4.00%
Stock options
Stock options, Non vested restricted stock awards and nonvested restricted stock units
Grants in period, weighted average grant date fair value (in dollars per share)			$ 15.04
Expected volatility (as a percent)			27.75%
Stock option activity
Outstanding, beginning of period (in shares) | shares			2,939,840
Granted (in shares) | shares			445,560
Forfeited (in shares) | shares			(45,263)
Exercised (in shares) | shares			(195,202)
Outstanding, end of period (in shares) | shares	3,144,935		3,144,935
Vested and expected to vest end of period (in shares) | shares	3,111,786		3,111,786
Exercisable, end of period (in shares) | shares	1,785,957		1,785,957
Weighted average exercise price of stock options
Outstanding, beginning of period (in dollars per share)			$ 55.13
Granted (in dollars per share)			64.08
Forfeited (in dollars per share)			51.07
Exercised (in dollars per share)			49.00
Outstanding, end of period (in dollars per share)	$ 56.84		56.84
Vested and expected to vest end of period (in dollars per share)	56.78		56.78
Exercisable, end of period (in dollars per share)	$ 53.13		$ 53.13
Assumptions used for estimating value of awards granted
Vesting period			3 years
Life of options (Expiration period)			10 years
Restricted stock awards
Nonvested restricted stock awards and units
Outstanding, beginning of period (in shares) | shares			1,109,622
Awarded (in shares) | shares			16,065
Vested (in shares) | shares			(20,115)
Outstanding, end of period (in shares) | shares	1,105,572		1,105,572
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)			$ 57.88
Awarded (in dollars per share)			65.36
Vested (in dollars per share)			67.12
Outstanding, end of period (in dollars per share)	$ 57.82		$ 57.82
Restricted stock awards | Minimum
Assumptions used for estimating value of awards granted
Vesting period			12 months
Restricted stock awards | Maximum
Assumptions used for estimating value of awards granted
Vesting period			42 months
Restricted Stock Units (RSUs)
Nonvested restricted stock awards and units
Outstanding, beginning of period (in shares) | shares			231,088
Awarded (in shares) | shares			51,521
Vested (in shares) | shares			(51,419)
Forfeited (in shares) | shares			(13,713)
Outstanding, end of period (in shares) | shares	217,477		217,477
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)			$ 61.53
Awarded (in dollars per share)			64.87
Vested (in dollars per share)			63.77
Forfeited (in dollars per share)			63.59
Outstanding, end of period (in dollars per share)	$ 61.66		$ 61.66
Assumptions used for estimating value of awards granted
Vesting period			3 years
Performance Based Restricted Stock Units ("PSUs")
Nonvested restricted stock awards and units
Outstanding, beginning of period (in shares) | shares			36,938
Awarded (in shares) | shares			65,067
Outstanding, end of period (in shares) | shares	102,005		102,005
Estimated fair value | $			$ 97.60
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)			$ 85.00
Awarded (in dollars per share)			97.60
Outstanding, end of period (in dollars per share)	$ 93.04		$ 93.04
Assumptions used for estimating value of awards granted
Vesting period			3 years
Expected dividend yield (as a percent)			0.00%
Risk-free interest rate (as a percent)			1.00%
Expected volatility, minimum (as a percent)			16.00%
Expected volatility, maximum (as a percent)			81.00%
Expected volatility, average (as a percent)			32.00%
Number of trading days considered for average share value			30
Number of companies in peer group | company			56
Performance Based Restricted Stock Units ("PSUs") | Minimum
Assumptions used for estimating value of awards granted
Percentage of shares to be settled			0.00%
Performance Based Restricted Stock Units ("PSUs") | Maximum
Assumptions used for estimating value of awards granted
Percentage of shares to be settled			200.00%