Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands					3 Months Ended					12 Months Ended
	Aug. 18, 2015	Dec. 10, 2014	Oct. 31, 2014	Oct. 17, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Issuance of common stock, net, shares	16,330,000
Proceeds from the issuance of common stock, net	$ 163,700									$ 162,963	$ 0	$ 0
Share price to the public (in usd per share)	$ 10.50
Dividends payable					$ 7,704				$ 3,946	$ 7,704	$ 3,946
Dividend, payable date										Jan. 15, 2015
Dividend, record date										Dec. 31, 2014
Dividends declared per common share (in usd per share)					$ 0.16	$ 0.16	$ 0.16	$ 0.16	$ 0.125	$ 0.64	$ 0.125
Over-Allotment Option [Member]
Class of Stock [Line Items]
Issuance of common stock, net, shares	2,130,000
Special Dividend [Member]
Class of Stock [Line Items]
Issuance of common stock, net, shares		8,974,249
Dividend, declared date				Oct. 17, 2014						Oct. 17, 2014
Dividends payable				$ 132,000
Dividend payable per share (in usd per share)				$ 5.88
Dividend, payable date		Dec. 10, 2014								Dec. 10, 2014
Dividend, record date			Oct. 31, 2014							Oct. 31, 2014
Cash portion of dividend		$ 33,000
Stock portion of dividend		$ 99,000