General - Stock Compensation (Details)	3 Months Ended
	Mar. 31, 2017 USD ($) company $ / shares shares	Mar. 31, 2016 USD ($)
Stock options, Non vested restricted stock awards and nonvested restricted stock units
Stock compensation expense | $	$ 10,100,000	$ 8,900,000
Benefits of tax deductions in excess of recognized stock compensation expense | $	$ 900,000	$ 300,000
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)	$ 17.10
Expected volatility (as a percent)	27.80%
Stock option activity
Outstanding, beginning of period (in shares) | shares	2,843,177
Granted (in shares) | shares	408,096
Forfeited (in shares) | shares	(4,750)
Exercised (in shares) | shares	(100,054)
Outstanding, end of period (in shares) | shares	3,146,469
Vested and expected to vest end of period (in shares) | shares	3,114,864
Exercisable, end of period (in shares) | shares	2,016,716
Weighted average exercise price of stock options
Outstanding, beginning of period (in dollars per share)	$ 57.42
Granted (in dollars per share)	69.21
Forfeited (in dollars per share)	61.85
Exercised (in dollars per share)	50.81
Outstanding, end of period (in dollars per share)	59.16
Vested and expected to vest end of period (in dollars per share)	59.09
Exercisable, end of period (in dollars per share)	$ 55.90
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	615,472
Outstanding, end of period (in shares) | shares	615,472
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)	$ 58.71
Outstanding, end of period (in dollars per share)	$ 58.71
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	200,178
Awarded (in shares) | shares	105,280
Vested (in shares) | shares	(117,069)
Forfeited (in shares) | shares	(3,295)
Outstanding, end of period (in shares) | shares	185,094
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)	$ 61.65
Awarded (in dollars per share)	68.50
Vested (in dollars per share)	60.52
Forfeited (in dollars per share)	63.26
Outstanding, end of period (in dollars per share)	$ 66.23
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	102,977
Awarded (in shares) | shares	101,989
Outstanding, end of period (in shares) | shares	204,966
Estimated fair value | $	$ 76.24
Weighted average exercise price of nonvested restricted stock award and units
Outstanding, beginning of period (in dollars per share)	$ 93.03
Awarded (in dollars per share)	76.24
Outstanding, end of period (in dollars per share)	$ 84.67
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)	1.54%
Expected volatility, minimum (as a percent)	18.00%
Expected volatility, maximum (as a percent)	61.00%
Expected volatility, average (as a percent)	33.00%
Number of trading days considered for average share value	30
Number of companies in peer group | company	51
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%