Diluted Earnings per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stockholders Equity Note Disclosure [Line Items]
Net income (loss) attributable to common stockholders - basic and diluted	$ 1,100		$ (7,267)		$ (1,662)		$ (4,614)		$ (5,584)		$ 30,501		$ 13,155		$ 12,005		$ (12,445)	$ 50,077	$ 18,605
Weighted average number of common shares outstanding																	28,584	28,230	27,848
Dilutive effect of outstanding stock options and restricted stock grants after application of the treasury stock method																		198	342
Dilutive shares outstanding																	28,584	28,428	28,190
Basic earnings (loss) per share attributable to common stockholders	$ 0.04		$ (0.25)		$ (0.06)		$ (0.16)		$ (0.20)		$ 1.08		$ 0.47		$ 0.43		$ (0.44)	$ 1.77	$ 0.67
Diluted earnings (loss) per share attributable to common stockholders	$ 0.04	[1]	$ (0.25)	[1]	$ (0.06)	[1]	$ (0.16)	[1]	$ (0.20)	[1]	$ 1.07	[1]	$ 0.46	[1]	$ 0.42	[1]	$ (0.44)	$ 1.76	$ 0.66

[1] See Note 13 for discussion on the computation of diluted shares outstanding.