Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 52,052	$ 56,933	$ 167,770	$ 165,691
Other Comprehensive Income (Loss), Net of Tax:
Net Unrealized Gains (Losses) on Investment Securities	5,405	(5,599)	28,533	(17,694)
Defined Benefit Plans	245	216	736	648
Total Other Comprehensive Income (Loss)	5,650	(5,383)	29,269	(17,046)
Comprehensive Income	$ 57,702	$ 51,550	$ 197,039	$ 148,645