CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 94,973	$ 82,000	$ 176,373	$ 163,694
Other Comprehensive Income
Net Changes in Fair Value of Cash Flow Hedges	78	121	297	336
Supplemental Executive Retirement Plan Adjustments	117	69	349	209
Total Other Comprehensive Income, Net of Tax	195	190	646	545
Total Comprehensive Income	$ 95,168	$ 82,190	$ 177,019	$ 164,239

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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