Stock-Based Compensation and Similar Arrangements (Tables)

12 Months Ended

Dec. 31, 2018

Share-based Compensation [Abstract]

Schedule of 2006 Plan Activity

The following table summarizes the activity under the 2006 Plan as of December 31, 2018:

	Number of shares of the Company’s Common Stock authorized for	Number of shares of the Company’s Common Stock remaining for	Number of shares of the Company’s Common Stock subject to
	issuance	future grants	Stock Options	Stock Grants
2006 Plan	5,400,000	1,356,820	908,588	52,131

Schedule of Stock-Based Compensation

The following table reflects the amount of stock-based compensation, for share settled awards issued to employees and non-employee directors, recorded in each financial statement line item for the years ended December 31, 2018, 2017 and 2016:

	Year Ended December 31,
	2018		2017		2016
Service expense	$	950	$	434	$	841
General and administrative expense	8,037		7,052		4,324
Equity in net loss (gain) of investees	137		76		18
(Loss) income from discontinued operations, net of tax	6		57		(29		)
Total stock-based compensation	$	9,130	$	7,619	$	5,154

Schedule of Stock-Based Compensation Valuation Assumptions

The fair value of each stock option awarded to employees is estimated on the date of grant using the Black-Scholes option-pricing formula based on the following assumptions for the years ended December 31, 2018 and 2017:

	Year Ended December 31,
	2018			2017
Expected dividend yield	0.0%			0.0%
Expected stock price volatility	26.47%	—	39.83%	19.5%	—	42.95%
Risk-free interest rate	2.26%	—	2.91%	1.0%	—	2.23%
Expected life of options (years)	1.29	—	6.50	0.03	—	6.50

Stock Option Activity

The following table summarizes the stock option activity for the year ended December 31, 2018:

	Year ended December 31, 2018
	Number of Shares Under Option		Weighted- average Exercise Price		Weighted- average Remaining Contractual Term	Aggregate Intrinsic Value
Balance at beginning of period, January 1	606,695		$	48.70
Granted	750,993		66.73
Exercised	(278,969	)	44.82
Forfeited/Canceled	(120,131	)	68.81
Expired	(50,000	)	61.33
Outstanding at end of period, December 31	908,588		$	61.44	2.40	$	4,348
Vested or expected to vest at end of period, December 31	871,651		$	61.01	2.49	$	4,348
Exercisable at end of period, December 31	263,897		$	50.28	1.98	$	2,570

Weighted-Average Grant Date Fair Value, Total Intrinsic Value, and Cash Received

The weighted-average grant date fair value for options granted, total intrinsic value and cash received by the Company related to options exercised during the years ended December 31, 2018, 2017 and 2016 were as follows:

	Year ended December 31,
	2018		2017		2016
Weighted-average grant date fair value per share	$	15.08	$	9.05	$	—
Options exercised:
Total intrinsic value	$	6,805	$	2,010	$	979
Cash received	$	12,413	$	1,921	$	4,108

Restricted Stock Activity

The following table summarizes the activity of the shares and weighted-average grant date fair value of the Company’s unvested restricted Common Stock during the year ended December 31, 2018:

	Shares		Weighted-average grant date fair value
Non-vested at beginning of period, January 1	64,779		$	44.82
Granted	20,242		$	66.07
Vested	(27,894	)	$	46.39
Forfeited or cancelled	(9,799	)	$	46.83
Non-vested at end of period, December 31	47,328		$	52.56

Stock Appreciation Rights Fair Value Assumptions

The fair value of the SOEUs was estimated as of December 31, 2018, 2017 and 2016 using the Black-Scholes option-pricing formula and amortized over the option’s graded vesting periods with the following assumptions:

	Year ended December 31,
	2018			2017			2016
Expected dividend yield	0.0%			0.0%			0.0%
Expected stock price volatility	27.82%	—	30.59%	23.36%	—	32.09%	35.71%	—	41.8%
Risk-free interest rate	2.50%	—	2.61%	1.75%	—	1.95%	1.11%	—	1.64%
Expected life of options (in years)	0.75	—	1.75	0.75	—	2.75	1.00	—	3.00

Performance Share, Fair Value Assumptions

The fair value of the awards granted in 2016 were estimated using the following assumptions:

	Year ended December 31, 2016
Forward interest rate	0.24%	—	2.71%
Expected Volatility	40.0%
Dividend Yield	—%
Fair Value of Total Pool	$12,870