Cash Flows as Previously Reported and as Changed (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Cash flows provided by operating activities:
Restricted cash and cash equivalents	$ 912	$ 199
Net cash provided by operating activities	124,734	65,292
Cash flows used in investing activities:
Restricted funds held for derivative collateral and legal matters	(180)	(5,405)
Net cash used in investing activities	(74,257)	(56,110)
Scenario, Previously Reported
Cash flows provided by operating activities:
Net cash provided by operating activities		65,491
Cash flows used in investing activities:
Restricted cash and cash equivalents		5,206
Net cash used in investing activities		(56,309)
As Changed
Cash flows provided by operating activities:
Restricted cash and cash equivalents		(199)
Net cash provided by operating activities		65,292
Cash flows used in investing activities:
Restricted funds held for derivative collateral and legal matters		5,405
Net cash used in investing activities		$ (56,110)

The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as investing activities.

+ References+ Details

The net cash from (used in) all of the entity's operating activities, including those of discontinued operations, of the reporting entity. Operating activities generally involve producing and delivering goods and providing services. Operating activity cash flows include transactions, adjustments, and changes in value that are not defined as investing or financing activities. While for technical reasons this element has no balance attribute, the default assumption is a debit balance consistent with its label.

+ References+ Details