Stockholders' equity (Tables)

12 Months Ended

Dec. 31, 2018

Stockholders' equity

Summary of stock option activity

The following table summarizes stock option activity for the years ended December 31, 2018 and 2017 (shares and intrinsic values in thousands):

				Weighted-
				average
		Weighted-		remaining	Aggregate
	Number of	average exercise		contractual	intrinsic
	shares	price		term	value
Outstanding at December 31, 2016	2,920	$	11.64	7.6	$	1,274
Granted	55	$	11.35	6.0		—
Exercised	—		—	—		—
Forfeited	(37)		10.39	—		—
Expired	(40)	$	11.51	—		—
Outstanding at December 31, 2017	2,898	$	11.62	6.5	$	1,738
Granted	109	$	12.84	6.0		—
Exercised	(67)		13.38	—		—
Forfeited	(24)		12.30	—		—
Expired	(6)	$	12.10	—		—
Outstanding at December 31, 2018	2,910	$	11.62	5.6	$	2,806
Vested at December 31, 2018	2,175	$	11.71	5.3	$	2,102
Exercisable at December 31, 2018	2,175	$	11.71	5.3	$	2,102

Summary of restricted share activity

The following table summarizes restricted share activity for the years ended December 31, 2018 and 2017 (shares in thousands):

	Number of	Weighted-average
	shares	grant date fair value
Outstanding at December 31, 2016	561	$	10.58
Granted	154		11.19
Vested	(203)		11.80
Forfeited	(8)		13.38
Outstanding at December 31, 2017	504	$	10.23
Granted	93		11.85
Vested	(218)		11.49
Forfeited	(9)		11.85
Outstanding at December 31, 2018	370	$	9.86

Time Based Stock Option | Black Scholes Pricing Model

Stockholders' equity

Schedule of valuation assumptions

Black-Scholes Option Valuation Assumptions	2018					2017
Risk-free interest rate	2.7	%	-	3.0	%	2.2	%
Dividend yield				—		—
Volatility	39.0	%	-	41.0	%	25.8	%
Weighted-average expected term (years)				6.0		6.0