Stockholders' Equity - Cash Dividends Declared to Stockholders (Detail) - Common Stock $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Per Share Amount (usd per share) | $ / shares	$ 0.625
Total Payment | $	$ 12,733
Installment One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Dec. 20, 2016
Record Date	Jan. 04, 2017
Payment Date	Jan. 17, 2017
Per Share Amount (usd per share) | $ / shares	$ 0.25
Total Payment | $	$ 5,128
Installment Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Mar. 01, 2017
Record Date	Mar. 17, 2017
Payment Date	Mar. 30, 2017
Per Share Amount (usd per share) | $ / shares	$ 0.125
Total Payment | $	$ 2,566
Installment Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Apr. 26, 2017
Record Date	May 23, 2017
Payment Date	Jun. 23, 2017
Per Share Amount (usd per share) | $ / shares	$ 0.125
Total Payment | $	$ 2,545
Installment Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Declaration Date	Jul. 26, 2017
Record Date	Aug. 18, 2017
Payment Date	Sep. 08, 2017
Per Share Amount (usd per share) | $ / shares	$ 0.125
Total Payment | $	$ 2,494