Components of Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss)		$ 10,295	$ 28,081
Weighted-average shares – basic		15,042	14,992
Effect of dilutive securities	[1]	39	134
Weighted-average shares – diluted		15,081	15,126
Net Income (Loss) Available to Common Stockholders, Basic		$ 10,295	$ 28,081

[1] The number of dilutive securities for the three months ended March 31, 2018 and 2017, which is attributable to RSUs and PRSUs, was determined under the “treasury stock” method.