Savings Plan - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Savings Plan, 401(k) Disclosure [Line Items]
Employees eligible compensation deferral for 401(k) Plan	The 401(k) Plan permits eligible employees of the Company and those of any Subsidiary to defer up to 60% of their eligible compensation on a pre-tax basis subject to certain maximum amounts. In addition, the Company will match 100% of the participant's contribution up to the first 3% and then 50% of the next 2% for a maximum potential match of 4%.
Employees eligible compensation deferral for 401(k) Plan	60.00%
401(k) Plan, employer matching percentage for the first 3% of participants' contribution	100.00%
401(k) Plan, employer matching percentage for the second 2% of participants' contribution	50.00%
Maximum potential employer match for 401(k) Plan	4.00%
Vested percentage for amounts contributed by the Company, after five years of employment	100.00%
Company's contribution to the 401(k) Plan	$ 1.1	$ 1.0	$ 0.8

- Definition

Description of the terms and benefits provided by the employer's defined contribution plans. A defined contribution plan provides benefits in return for services rendered, provides an individual account for each participant, and has terms that specify how contributions to the individual's account are to be determined rather than the amount of benefits the individual is to receive. Under a defined contribution pension plan, the benefits a participant will receive depend solely on the amount contributed to the participant's account, the returns earned on investments of those contributions, and forfeitures of other participants' benefits that may be allocated to such participant's account. A description of the plan(s) including employee groups covered, the basis for determining contributions, and the nature and effects of significant matters affecting comparability of information for all periods presented.

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