Shareholders' Equity - Summary of Changes in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Income Loss [Line Items]
Balance, beginning of period	$ 1,491	$ 6,678
Other comprehensive loss before reclassifications	(1,075)	(845)
Net current-period other comprehensive loss	(1,075)	(845)
Balance, end of period	416	5,833
Balance, beginning of period	(8,208)	(9,048)
Net current-period other comprehensive loss
Balance, end of period	(8,208)	(9,048)
Balance, beginning of period	(6,717)	(2,370)
Other comprehensive loss before reclassifications	(1,075)	(845)
Less: Amounts reclassified from accumulated other comprehensive income (loss)
Net current-period other comprehensive loss	(1,075)	(845)
Balance, end of period	$ (7,792)	$ (3,215)