Reconciliation of Numerator and Denominator of Basic and Diluted Net Income (Loss) Per Share (Detail) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from denominator in computation of diluted net income per share	3,682	1,446	3,597	1,944
Equity Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from denominator in computation of diluted net income per share	4	71	8	302
Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from denominator in computation of diluted net income per share	2,737	1,103	2,562	1,319
Performance Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from denominator in computation of diluted net income per share	201	115	455	267
Stock Purchase Rights
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from denominator in computation of diluted net income per share	740	157	572	56