Convertible and Non-Recourse Notes (Future Minimum Principal Payments) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Debt Instrument [Line Items]
2013	$ 0
2014	0
2015	335,250
Total	335,250
Series 2012 Notes [Member]
Debt Instrument [Line Items]
2013	0
2014	0
2015	179,000
Total	179,000
May 2015 Notes [Member]
Debt Instrument [Line Items]
2013	0
2014	0
2015	155,250
Total	155,250
February 2015 Notes [Member]
Debt Instrument [Line Items]
2013	0
2014	0
2015	1,000
Total	$ 1,000