Company's Stock Option RSU and SAR Grants to Equity Incentive Plans (Parenthetical) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010	Jan. 31, 2009	Mar. 31, 2013
Equity Incentive Plan [Line Items]
Aggregate intrinsic value on the share price of the Company's common stock					8.07
Maximum
Equity Incentive Plan [Line Items]
Convertible for a maximum number of shares, grants	50.00%	66.67%	75.00%	50.00%
Outstanding share issuable upon exercise					6,763
Exercisable share issuable upon exercise					4,856