Stockholders' equity (Tables)

9 Months Ended

Sep. 30, 2017

Equity incentive plans

Summary of stock option activity

The following table summarizes stock option activity for the nine months ended September 30, 2017 (shares and intrinsic value in thousands):

	Number of shares		Weighted-average exercise price		Weighted-average remaining contractual term	Aggregate intrinsic value
Outstanding at December 31, 2016	2,920		$	11.64	7.6	$	1,274
Granted	—		—		—	—
Exercised	—		—		—	—
Forfeited	(37	)	13.26		—	—
Expired	(40	)	11.51		—	—
Outstanding at September 30, 2017	2,843		$	11.62	6.7	$	2,311
Vested at September 30, 2017	1,875		$	11.67	6.0	$	1,760
Exercisable at September 30, 2017	1,875		$	11.67	6.0	$	1,760

Summary of restricted share activity

The following table summarizes restricted share activity for the nine months ended September 30, 2017 (shares in thousands):

	Number of shares		Weighted-average grant date fair value
Outstanding at December 31, 2016	561		$	10.58
Granted	99		11.10
Vested	(204	)	11.80
Forfeited	(8	)	13.38
Outstanding at September 30, 2017	448		$	10.09

Time Based Stock Option | Black Scholes Pricing Model

Equity incentive plans

Schedule of valuation assumptions

Black-Scholes Option Valuation Assumptions	Nine Months Ended September 30, 2017	Year Ended December 31, 2016
Risk-free interest rate	—	1.6%-2.4%
Dividend yield	—	—
Volatility	—	26.4%-32.4%
Weighted-average expected term (years)t	—	6.2