Retirement Plan (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Maximum defined contribution plan employee contribution, percentage	100.00%
Percentage of participant contribution considered for first condition of plan	100.00%
Percentage of employees eligible earnings subject to match	The Company matches 100% of the first 3% of employee contributions and 50% of the next 2% of employee contributions.
Percentage of participant salary under first condition of plan	3.00%
Percentage of participant contribution considered for second condition of plan	50.00%
Percentage of participant salary under second condition of plan	2.00%
Employer matching contributions to the plan	$ 1.3	$ 0.6	$ 0.5

The maximum percentage of compensation that can be contributed by employees into the 401K retirement plan.

No definition available.

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- Definition

Maximum percentage of employee's eligible earnings subject to the entity's discretionary matching percentage.

+ References

No definition available.

+ Details

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- Definition

Percentage of participant contribution considered for first condition of plan.

+ References

No definition available.

+ Details

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- Definition

Percentage of participant contribution considered for second condition of plan.

+ References

No definition available.

+ Details

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- Definition

Percentage of participant salary under first condition of plan.

+ References

No definition available.

+ Details

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- Definition

Percentage of participant salary under second condition of plan.

+ References

No definition available.

+ Details

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- Details

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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