Reconciliation Of Our Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009
Income Tax Contingency [Line Items]
Beginning balance	$ 0	$ 0	$ 0
Additions based on tax positions related to current year	0	0
Reductions for tax positions of prior years	0	0
Reductions due to expiration of statute of limitations	0	0
Settlements with taxing authorities	0	0
Ending Balance	$ 0	$ 0	$ 0