Share-Based Compensation Expense (Schedule of Restricted Stock by Price Range (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Restricted Stock [Member]
Weighted average measurement date price, outstanding at end of the period	$ 15.05	$ 15.00
Number of shares, outstanding at end of the period	590	1,052
Restricted Stock Units (RSUs) [Member]
Weighted average measurement date price, outstanding at end of the period	$ 11.56	$ 10.16
Number of shares, outstanding at end of the period	1,208	702
$0.00 - $9.99 [Member] | Restricted Stock [Member]
Weighted average measurement date price, outstanding at end of the period	$ 9.45
Number of shares, outstanding at end of the period	89
$0.00 - $9.99 [Member] | Restricted Stock Units (RSUs) [Member]
Weighted average measurement date price, outstanding at end of the period	$ 9.82
Number of shares, outstanding at end of the period	547
$10.00-$14.99 [Member] | Restricted Stock [Member]
Weighted average measurement date price, outstanding at end of the period	$ 11.86
Number of shares, outstanding at end of the period	197
$10.00-$14.99 [Member] | Restricted Stock Units (RSUs) [Member]
Weighted average measurement date price, outstanding at end of the period	$ 12.92
Number of shares, outstanding at end of the period	649
$15.00-$19.99 [Member] | Restricted Stock [Member]
Weighted average measurement date price, outstanding at end of the period	$ 18.65
Number of shares, outstanding at end of the period	284
$15.00-$19.99 [Member] | Restricted Stock Units (RSUs) [Member]
Weighted average measurement date price, outstanding at end of the period	$ 16.45
Number of shares, outstanding at end of the period	12
$20.00 and above [Member] | Restricted Stock [Member]
Weighted average measurement date price, outstanding at end of the period	$ 20.21
Number of shares, outstanding at end of the period	20