Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Preferred stock issued		0		0	0
Silver Creek [Member]
Subsequent Event [Line Items]
Net cash proceeds from stock issuance				$ 2,599
Ownership interest percentage held by parent and its de facto agents		51.00%		51.00%
Silver Creek [Member] | Series C Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred stock issued		400	1,400	400
Preferred stock price per share		$ 1.50	$ 1.50	$ 1.50
Net cash proceeds from stock issuance		$ 600	$ 2,000
Silver Creek [Member] | Series C Preferred Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Preferred stock issued	1,700
Preferred stock price per share	$ 1.50
Net cash proceeds from stock issuance	$ 2,600