CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 124,438	$ 127,794	$ 102,338
Other Comprehensive Income (Loss)
Net of Income Tax (Expense) Benefit of $(420), $(821), and $(1,140)	652	1,261	1,675
Supplemental Executive Retirement Plan Adjustments:	(643)	101	(1,725)
Total Other Comprehensive Income (Loss), Net of Tax	9	1,362	(50)
Total Comprehensive Income	$ 124,447	$ 129,156	$ 102,288