Income Taxes - Unrecognized Tax Benefits Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Unrecognized Tax Benefits Reconciliation
Balance at beginning of year	$ 45,987us-gaap_UnrecognizedTaxBenefits	$ 46,980us-gaap_UnrecognizedTaxBenefits	$ 63,498us-gaap_UnrecognizedTaxBenefits
Additions based on tax positions taken during a prior period	3,792	22,170	448
Reductions based on tax positions taken during a prior period	(7,737)	(3,684)	(11,824)
Additions based on tax positions taken during the current period	5,518	7,593	8,014
Reductions related to settlement of tax matters	(317)	(24,450)	(8,288)
Reductions related to a lapse of applicable statute of limitations	(2,542)	(2,622)	(4,868)
Balance at end of year	44,701us-gaap_UnrecognizedTaxBenefits	45,987us-gaap_UnrecognizedTaxBenefits	46,980us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 12,173	$ 10,637

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

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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 accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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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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