Employee Benefits (Retirement Plans And Other Postretirement Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,905	$ 2,100	$ 8,597	$ 8,514
Interest cost	3,265	3,625	14,135	14,797
Expected return on plan assets	(4,712)	(4,947)	(19,560)	(18,966)
Amortization of prior service benefit	(878)	(888)	(3,496)	(3,535)
Amortization of net (gain) loss	1,888	2,750	9,785	9,830
Net periodic benefit cost (benefit)	1,468	2,640	9,461	10,640
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	715	875	3,294	3,020
Interest cost	873	1,025	3,883	4,363
Expected return on plan assets	(460)	(525)	(2,005)	(2,116)
Amortization of prior service benefit	(788)	(775)	(3,081)	(4,328)
Amortization of net (gain) loss	(665)	(500)	(2,190)	(2,521)
Net periodic benefit cost (benefit)	$ (325)	$ 100	$ (99)	$ (1,582)