Share-based incentives (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of the Restricted Common Stock Award Activity

A summary of the restricted common stock award activity during the year ended December 31, 2015 is presented below:

	Shares		Weighted-Average Grant-Date Fair Value per Share ($)
Nonvested balance at January 1, 2015	205,119		29.78
Granted	118,506		37.16
Adjustment for performance-based shares	19,610		37.18
Vested	(78,115	)	25.78
Forfeited	(12,930	)	31.43
Nonvested balance at December 31, 2015	252,190		34.88