Segments and Related Information (Reconciliation of Consolidated Income before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
EBITDA Reconciliation:
Income before income taxes	$ 145,633	$ 107,579	$ 299,405	$ 314,330
Interest expense, net	22,330	17,578	60,183	44,966
Depreciation and amortization	54,863	50,101	156,478	138,384
Consolidated EBITDA	$ 222,800	$ 175,300	$ 516,100	$ 497,700

Earnings before interest, taxes, depreciation and amortization ("EBITDA"), a non-U.S. GAAP financial measure.

No definition available.

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

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- Definition

Amount of interest revenue (income derived from investments in debt securities and on cash and cash equivalents) net of interest expense (cost of borrowed funds accounted for as interest).

+ References

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- References

No definition available.

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