Share-based compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Outstanding Restricted Shares, Phantom Share Units, SARs and Restricted Stock Units

A summary of the Company’s outstanding restricted shares, phantom share units, SARs and restricted stock units as of December 31, 2016 is presented below:

	Restricted shares					Phantom share units					Stock appreciation rights					Restricted stock units
	Number			W.A.grant		Number			W.A. grant		Number of			W.A. grant		Number			W.A. grant
	of shares			date FV		of units			date FV		SARs			date FV		of units			date FV
December 31, 2013		48,880		$	17.01		657,000		$	14.02		7,072,945		$	2.32		—		$	—
Granted		43,936			22.57		70,000			23.04		—			—		72,314			23.03
Vested		(48,880	)		17.01		—			—		—			—		(37,238	)		23.03
Exercised		—			—		—			—		(1,193,529	)		2.42		—			—
Exchanged		—			—		(20,000	)		19.00		—			—		—			—
December 31, 2014		43,936			22.57		707,000			14.77		5,879,416			2.30		35,076			23.03
Granted		51,368			18.39		100,000			18.24		—			—		38,142			20.21
Vested		(45,924	)		22.39		—			—		—			—		(35,195	)		22.01
Exchanged		—			—		(110,000	)		16.21		—			—		—			—
Cancelled		(4,433	)		18.39		(49,999	)		19.66		(2,605	)		3.65		(5,195	)		21.86
December 31, 2015		44,947			18.39		647,001			14.73		5,876,811			2.30		32,828			21.03
Granted		56,861		15.48			60,000			18.84		—			—		528,232		16.57
Vested		(44,947	)	18.39			—			—		—			—		(37,374	)	18.56
Exchanged		—			—		(70,000	)	19.91			—			—		—			—
Expired		—			—		—			—		(3,438,614	)		2.26		—			—
Cancelled		—			—		—			—		—			—		(299	)	20.21
December 31, 2016		56,861		$	15.48		637,001		$	14.55		2,438,197		$	2.29		523,387		$	16.71

Schedule of Assumptions to Calculate Fair Value of Performance Stock Units

The assumptions used in the Monte Carlo model to calculate the grant date fair value of the performance stock units were as follows:

Average expected term	3.03 years
Expected volatility		32.25	%
Dividend yield		8.95	%
Average risk free rate		1.38	%

Schedule of Information about Performance Stock Units Granted

The following table provides information about the performance stock units granted:

			Performance Vesting Price		Time Vesting
Tranche	Number of PSUs		per Share		(continued employment)
1		127,316	$	17.60	May 31, 2017
2		140,806	$	18.48	May 31, 2018
3		155,212	$	19.40	May 31, 2019
4		171,612	$	20.37	May 31, 2020
5		191,201	$	21.39	May 31, 2021
		786,147