Income Taxes (Summary of Changes in Gross Amount of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Uncertainties [Abstract]
Unrealized tax benefit, beginning balance	$ 35,388	$ 34,798	$ 36,928
Additions based on tax positions related to the current year	3,550	6,299	6,116
Additions based on tax positions related to prior years	4,255	0	0
Payments related to items settled with taxing authorities	(2,792)	0	(195)
Reduction due to lapse of statute of limitations and settlements	(6,635)	(5,709)	(8,051)
Unrealized tax benefit, ending balance	$ 33,766	$ 35,388	$ 34,798

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Amount of unrecognized tax benefits.

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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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