Employee Benefits (Retirement Plans And Other Postretirement Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,476	$ 2,801	$ 7,429	$ 8,316	$ 10,201	$ 10,446
Interest cost	3,614	3,214	10,841	9,659	14,060	12,924
Expected return on plan assets	(5,373)	(5,176)	(16,119)	(15,806)	(21,389)	(20,603)
Amortization of net (gain) loss	1,449	2,214	4,345	6,414	6,484	8,527
Amortization of prior service benefit	(877)	(875)	(2,630)	(2,630)	(3,506)	(3,506)
Net periodic benefit cost (benefit)	1,289	2,178	3,866	5,953	5,850	7,788
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	606	696	1,817	2,096	2,516	2,655
Interest cost	614	559	1,842	1,689	2,405	2,370
Expected return on plan assets	(530)	(602)	(1,590)	(1,827)	(2,198)	(2,304)
Amortization of net (gain) loss	(595)	(574)	(1,783)	(1,624)	(2,325)	(2,044)
Amortization of prior service benefit	(1,308)	(1,538)	(3,925)	(4,613)	(5,463)	(6,151)
Net periodic benefit cost (benefit)	$ (1,213)	$ (1,459)	$ (3,639)	$ (4,279)	$ (5,065)	$ (5,474)