Earnings (Loss) Per Share - Computation of Earnings (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted average shares:
Weighted average common shares outstanding	50,789	50,693	51,566
Effect of dilutive securities outstanding	591	370	277
Diluted weighted average shares outstanding	51,380	51,063	51,843
Earnings (loss):
Income (loss) from continuing operations	$ 32,429	$ 134,225	$ 121,897
Income from discontinued operations	0	133	1,007
Net income (loss)	$ 32,429us-gaap_NetIncomeLoss	$ 134,358us-gaap_NetIncomeLoss	$ 122,904us-gaap_NetIncomeLoss
Basic per share amounts:
Income (loss) from continuing operations	$ 0.64	$ 2.65	$ 2.36
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.02
Net income (loss)	$ 0.64us-gaap_EarningsPerShareBasic	$ 2.65us-gaap_EarningsPerShareBasic	$ 2.38us-gaap_EarningsPerShareBasic
Diluted per share amounts:
Income (loss) from continuing operations	$ 0.63	$ 2.63	$ 2.35
Income from discontinued operations	$ 0.00	$ 0.00	$ 0.02
Net income (loss)	$ 0.63us-gaap_EarningsPerShareDiluted	$ 2.63us-gaap_EarningsPerShareDiluted	$ 2.37us-gaap_EarningsPerShareDiluted

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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