Commitments and Contingencies (Details) (Office space, trailers and certain equipment, USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Office space, trailers and certain equipment
Remaining annual minimum payments under operating leases
Remainder of 2012	$ 1.5
2013	0.6
2014	0.5
2015	0.5
2016	0.5
Total remaining annual minimum payments under operating leases	$ 3.6

The total of future contractually required payments on leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fifth year of the balance sheet date relating to leases defined as operating.

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- Definition

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fourth year of the balance sheet date relating to leases defined as operating.

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- Definition

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the third year of the balance sheet date relating to leases defined as operating.

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- Definition

For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the second year of the balance sheet date relating to leases defined as operating.

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