Reconciliation of Total Segment Operating Income to Total Consolidated Income before Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Operating income (loss)	$ 8,115	$ 10,456	$ 41,581	$ 30,805
Other income (expense), net	4		(17)	(1)
Consolidated income before income taxes	8,119	10,456	41,564	30,804
Total segment operating income
Segment Reporting Information [Line Items]
Operating income (loss)	15,631	16,356	63,984	49,315
Other Reconciling Items
Segment Reporting Information [Line Items]
Operating income (loss)	$ (7,516)	$ (5,900)	$ (22,403)	$ (18,510)