Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension and Supplemental Executive Retirement Plans [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 2,203	$ 2,952	$ 4,283	$ 5,669
Interest Cost	3,985	3,845	7,994	7,644
Expected Return on Assets	(5,257)	(5,034)	(10,515)	(10,072)
Recognized net actuarial loss	250	1,557	541	3,073
Amortization of prior service cost	(423)	127	(465)	252
Net periodic benefit cost	758	3,447	1,838	6,566
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	152	212	329	406
Interest Cost	144	156	327	309
Expected Return on Assets	(1,163)	(920)	(2,324)	(1,840)
Recognized net actuarial loss	(145)	0	(217)	0
Amortization of prior service cost	(1,662)	(1,662)	(3,325)	(3,324)
Net periodic benefit cost	$ (2,674)	$ (2,214)	$ (5,210)	$ (4,449)