Supplemental Financial Information (Details 1) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Prepaid expenses and other current assets
Rig spare parts and supplies	$ 51,175	$ 50,288
Deferred mobilization costs	60,396	76,868
Prepaid insurance	27,743	9,587
Deferred tax assets	9,557	9,557
Deposits	724	827
Prepaid taxes	32,865	20,347
FOREX contracts	8,410	4,326
Other	5,819	5,353
Total	$ 196,689	$ 177,153

Prepaid Expenses and Other Current Assets.

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Non-capitalized spare parts and supplies for use on drilling rigs.

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Carrying value of amounts transferred to third parties for security purposes that are expected to be returned or applied towards payment within one year or during the operating cycle, if shorter.

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Fair value as of the balance sheet date of all foreign currency derivative assets designated as cash flow hedging instruments.

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Aggregate carrying amount, as of the balance sheet date, of current assets not separately disclosed in the balance sheet. Current assets are expected to be realized or consumed within one year (or the normal operating cycle, if longer).

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Net amount of other deferred costs capitalized at the end of the reporting period. Does not include deferred finance costs or deferred acquisition costs of insurance companies.

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Carrying amount as of the balance sheet date of unamortized costs of insurance coverage, which will be charged against earnings ratably over the period in which contractually agreed upon coverage's will be in effect; such periods expire within one year or the normal operating cycle, if longer.

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Carrying amount as of the balance sheet date of payments made in advance for income and other taxes, which will be charged against earnings within one year or the normal operating cycle, if longer.

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