Components of Change in Fair Value Associated With Green Bay Option (Detail) (Green Bay Option, USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Green Bay Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning Balance	$ (11,398)	$ (8,030)
Add: Mark to market fair value adjustment	12	(3,368)
Ending Balance	$ (11,386)	$ (11,398)

Adjustment to the amount at which a liability incurred or settled in a current transaction between willing parties, that is, other than in a forced or liquidation sale.

No definition available.

Name:	us-gaap_LiabilitiesFairValueAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration