Long Lived Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	$ 1,689,762	$ 1,956,346	$ 1,755,392
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	1,332,762	1,686,088	1,536,583
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	67,536	81,472	89,980
Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	274,395	174,854	115,245
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	14,859	13,932	13,584
Pacific Rim and Far East
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, primarily power plants and related assets	$ 210