Shareholders' equity (Tables)

3 Months Ended

Mar. 31, 2015

Shareholders' equity.

Summary of Stock Option Activity under Plan

	Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (1) (in thousands)
Options outstanding at January 1, 2014	1,190,000		$	15.48	9.3	$	862
Granted	970,000		16.63
Exercised	—		—
Forfeited	(41,250	)	16.18
Options outstanding at March 31, 2014	2,118,750		$	15.99	9.4	$	1,532
Options exercisable at March 31, 2014	160,000		$	15.00	8.5	$	274
Options outstanding at January 1, 2015	2,165,000		$	16.17	8.8	$	1,890
Granted	553,500		16.48
Exercised	—		—
Forfeited	(110,500	)	16.57
Options outstanding at March 31, 2015	2,608,000		$	16.22	8.7	$	1,064
Options exercisable at March 31, 2015	597,500		$	15.80	7.8	$	466

(1) Intrinsic value for activities other than exercises is defined as the difference between the grant price and the market value on the last trading day of the period for those stock options where the market value is greater than the exercise price. For exercises, intrinsic value is defined as the difference between the grant price and the market value on the date of exercise.

Summary of Black-Scholes Option Pricing Model Inputs used for Valuation of Stock Options Outstanding

	2015			2014
Weighted-average fair value	$	4.57		$	5.01
Expected term (years)	7.0			7.0
Dividend yield	3.0		%	3.0		%
Volatility	36.0		%	38.5		%
Risk-free interest rate	1.9		%	2.2		%

Summary of restricted stock units activity under Plan

	2015		2014
Restricted stock units at beginning of period	85,000		—
Units awarded	42,000		92,000
Units vested	(21,250	)	—
Units forfeited	(6,000	)	(2,000	)
Restricted stock units at end of the period	99,750		90,000