Notes Payable and Other Indebtedness - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Notes Payable [Line Items]
Promissory notes and other forms of indebtedness	$ 1.5	$ 1.7
Weighted average interest rate	9.00%	9.00%	9.00%
Uncommitted letter of credit facility	35.0
Debt support standby letters of credit	19.7	22.0
Service fee percentage	1.25%
Line of credit facility, expiry date	Aug. 31, 2013
Standby Letters of Credit
Notes Payable [Line Items]
Promissory notes and other forms of indebtedness collateralized	1.5
Standby Letters Of Credit Used For Collateral Requirements
Notes Payable [Line Items]
Letters of credit outstanding	$ 18.1	$ 20.2