Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012 As Reported [Member]	Mar. 31, 2011 As Reported [Member]	Jun. 30, 2011 As Reported [Member]	Mar. 31, 2012 As Changed [Member]	Mar. 31, 2011 As Changed [Member]	Jun. 30, 2011 As Changed [Member]
Cash flows provided by operating activities:
Restricted cash and cash equivalents	$ 1,633	$ 1,588				$ 5,661	$ 2,438	$ 1,588
Net cash provided by operating activities	79,575	37,614	45,179	23,413	36,026	50,840	25,851	37,614
Cash flows used in investing activities:
Restricted cash and cash equivalents			5,661	2,753	6,993
Restricted funds held for derivative collateral and legal matter	180	5,405					315	5,405
Net cash used in investing activities	$ (50,274)	$ (32,871)	$ (11,215)	$ (11,915)	$ (31,283)	$ (16,876)	$ (14,353)	$ (32,871)

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.

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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.

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