Revenues from Major Customers - Additional Information (Detail)	12 Months Ended
Dec. 31, 2012
Revenue, Major Customer [Line Items]
Minimum Percentage of revenue	10.00%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration