CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 188,323	$ 176,668	$ 124,438
Net Changes in Fair Value of Cash Flow Hedges:
Net of Income Tax (Expense) Benefit of $(121)	364
Net of Income Tax (Expense) Benefit of $(305), and $(420)		485	652
Supplemental Executive Retirement Plan Adjustments:
Net of Income Tax (Expense) Benefit of $(747), $637, and $399	2,026	(2,156)	(643)
Total Other Comprehensive Income (Loss), Net of Tax	2,390	(1,671)	9
Total Comprehensive Income	$ 190,713	$ 174,997	$ 124,447