Stockholders' equity (Tables)

3 Months Ended

Mar. 31, 2017

Equity incentive plans

Summary of stock option activity

The following table summarizes stock option activity for the three months ended March 31, 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	—	—		—	—
Expired	—	—		—	—
Outstanding at March 31, 2017	2,920	$	11.64	7.4	$	2,010
Vested at March 31, 2017	1,565	$	11.59	6.3	$	1,535
Exercisable at March 31, 2017	1,565	$	11.59	6.3	$	1,535

Summary of restricted share activity

The following table summarizes restricted share activity for the three months ended March 31, 2017 (shares in thousands):

	Number of shares	Weighted-average grant date fair value
Outstanding at December 31, 2016	561	$	10.58
Granted	—	—
Vested	—	—
Forfeited	—	—
Outstanding at March 31, 2017	561	$	10.58

Time Based Stock Option | Black Scholes Pricing Model

Equity incentive plans

Schedule of valuation assumptions

Black-Scholes Option Valuation Assumptions	Three Months Ended March 31, 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)	—	6.2