Purchase of Common Shares (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2014	Jun. 30, 2015	Dec. 31, 2014
Stock Repurchase Program [Abstract]
Stock repurchase program, authorized amount	$ 40,000,000
Stock repurchase program, expected duration	5 years
Stock repurchased during period, shares		350,000	43,500
Stock repurchased during period, average (USD per share)		$ 8.83	$ 9.98