Shareholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Jul. 28, 2016
Stockholders Equity Note [Line Items]
Investment subject to foreign currency fluctuations	$ 15,626,000		$ 15,626,000
Cumulative foreign currency translation loss	(33,649,000)		(33,649,000)		$ (34,326,000)
Income tax (benefit) expense	$ (499,000)	$ (11,342,000)	(211,000)	$ (23,443,000)
Foreign Currency Exchange Gain (Loss), Net
Stockholders Equity Note [Line Items]
Income tax (benefit) expense			0
ATM Program | Cowen and Company LLC
Stockholders Equity Note [Line Items]
Aggregate offering price authorized						$ 75,000,000
Proceeds from sale of common stock under ATM program gross			46,612,000
Proceeds from sale of common stock under ATM program			45,564,000
Commissions paid			$ 1,048,000
ATM Program | Common Stock | Cowen and Company LLC
Stockholders Equity Note [Line Items]
Shares sold under ATM program			3,405,709
Average price per share	$ 13.69		$ 13.69