Employee Benefits (Retirement Plans And Other Postretirement Benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,191	$ 2,394	$ 6,001	$ 6,594	$ 8,199	$ 8,707
Interest cost	3,250	3,622	9,780	10,872	13,403	14,563
Expected return on plan assets	(4,734)	(4,951)	(14,159)	(14,846)	(19,108)	(19,528)
Amortization of prior service benefit	(875)	(855)	(2,630)	(2,630)	(3,506)	(3,506)
Amortization of net (gain) loss	1,730	2,485	5,505	7,985	8,167	10,267
Net periodic benefit cost (benefit)	1,562	2,695	4,497	7,975	7,155	10,503
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	749	841	2,179	2,591	3,042	3,302
Interest cost	871	976	2,616	3,026	3,625	4,142
Expected return on plan assets	(452)	(503)	(1,372)	(1,553)	(1,889)	(2,082)
Amortization of prior service benefit	(788)	(751)	(2,363)	(2,301)	(3,130)	(3,490)
Amortization of net (gain) loss	(643)	(519)	(1,973)	(1,519)	(2,479)	(2,186)
Net periodic benefit cost (benefit)	$ (263)	$ 44	$ (913)	$ 244	$ (831)	$ (314)