Share-based compensation (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015 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, 2012		63,653		$	14.17		562,000		$	13.13		5,674,148		$	2.03		—		$	—
Granted		54,990			17.01		95,000			19.30		1,664,457			3.51		—			—
Vested		(65,578	)		14.25		—			—		—			—		—			—
Exercised		—			—		—			—		(241,906	)		3.65		—			—
Cancelled		(4,185	)		17.01		—			—		(23,754	)		3.51		—			—
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		—			—		—			—
Cancelled		—			—		—			—		—			—		—			—
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

Schedule of Assumptions to Calculate Fair Value of Stock Appreciation Rights

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

	2013
Average expected term	3.8years
Expected volatility		39.73	%
Dividend yield		4.97	%
Average risk free rate		0.50	%

Schedule of Information about Three Tranches of SARs Granted

The following table provides information about the three tranches of SARs granted:

				Number of SARs granted
	Base price		Expiration date	2013
Tranche 1	$	21.50	December 7, 2015		531,885
Tranche 2		24.00	December 7, 2016		556,946
Tranche 3		26.50	December 7, 2017		575,626
Total					1,664,457