Income Taxes - Summary of Unrecognized Tax Benefits (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning of year	$ 7,168us-gaap_UnrecognizedTaxBenefits	$ 5,140us-gaap_UnrecognizedTaxBenefits	$ 10,104us-gaap_UnrecognizedTaxBenefits
Additions based on tax positions related to the current year	432	100	244
Reductions for explration statutes of limitations	1,572	(1,225)	(225)
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	254	3,490	3,335
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(707)	(337)	(8,193)
Settlements	0	0	(125)
Balance at end of year	$ 5,575us-gaap_UnrecognizedTaxBenefits	$ 7,168us-gaap_UnrecognizedTaxBenefits	$ 5,140us-gaap_UnrecognizedTaxBenefits

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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-Name Accounting Standards Codification

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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