Shareholders' Equity - Summary of Common Shares Outstanding (Details 3) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Roll forward of common shares outstanding
Balance at the beginning of the year, shares	32,762,494	32,548,477
Repurchases, shares	0	0
Restricted share issuances, shares	175,972	214,017
Balance at the end of the period, shares	32,938,466	32,762,494