Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

The following table summarizes the Company’s stock option activity (in thousands, except per share data and years) for the periods indicated:

	Stock Options Outstanding
				Weighted Average		Aggregate		Weighted Average
				Exercise Price		Intrinsic		Remaining Contractual
	Shares			Per Share		Value		Term (Years)
Balance as of January 1, 2014		600		$	92.84
Granted		745			125.46
Exercised		(9	)		92.84	$	653
Forfeited/Expired		(135	)		104.48
Balance as of December 31, 2014		1,201		$	111.77
Granted		380			178.93
Exercised		(91	)		105.25	$	6,367
Forfeited/Expired		(167	)		131.31
Balance as of December 31, 2015		1,323		$	129.04
Granted	45			189.62
Exercised		(112	)	97.82		$	8,102
Forfeited/Expired		(370	)	110.28
Balance as of December 31, 2016		886		$	143.89
Exercisable as of December 31, 2016		345		$	135.25	$	21,520	7.6
Expected to vest as of December 31, 2016		541		$	149.39		26,303	7.9
Total		886		$	143.89	$	47,823	7.7

Range Of Exercise Prices

Stock options outstanding as of December 31, 2016 are comprised of the following range of exercise prices per share (in thousands, except per share data and years):

	Stock Options Outstanding at December 31, 2016
			Weighted Average		Weighted Average
			Exercise Price		Remaining Contractual
Range of Exercise Prices per Share	Shares		Per Share		Term (Years)
$117.85 - $120.00		30	$	118.63	7.3
$120.01 - $150.00		510	$	121.43	7.3
$150.01 - $180.00		216	$	167.21	8.2
$180.01 - $201.25		130	$	198.99	8.8
Total		886	$	143.89		7.7

Assumptions Used in Black-Scholes Pricing Model

The weighted average grant date fair value of stock option awards using the Black-Scholes option pricing model was $75.54, $73.86, and $55.84 for each share subject to a stock option granted during the years ended December 31, 2016, 2015, and 2014, respectively, based on the following assumptions:

	Years Ended December 31,
	2016	2015	2014
Expected term of options in years	6.3	6.3	6.3
Expected volatility	38.5%	39.0% - 40.2%	41.5% - 42.5%
Risk-free interest rate	1.4% - 1.6%	1.5% - 2.0%	2.1% - 2.3%
Expected dividend yield	0.0%	0.0%	0.0%