Retirement Benefits (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 31, 2013	Jun. 30, 2013 Pension	Jun. 30, 2012 Pension	Jun. 30, 2013 Pension	Jun. 30, 2012 Pension	Jun. 30, 2013 Pension	Jun. 30, 2012 Pension	Jun. 30, 2013 SERP	Jun. 30, 2012 SERP	Jun. 30, 2013 SERP	Jun. 30, 2012 SERP	Jun. 30, 2013 SERP	Jun. 30, 2012 SERP	Jun. 30, 2013 OPEB	Jun. 30, 2012 OPEB	Jun. 30, 2013 OPEB	Jun. 30, 2012 OPEB	Jun. 30, 2013 OPEB	Jun. 30, 2012 OPEB
Net Periodic Pension Benefit Cost:
Service cost		$ 1,859,000	$ 1,628,000	$ 3,727,000	$ 3,256,000	$ 6,732,000	$ 6,054,000	$ 52,000	$ 7,000	$ 67,000	$ 15,000	$ 104,000	$ 62,000	$ 715,000	$ 565,000	$ 1,470,000	$ 1,129,000	$ 2,742,000	$ 2,262,000
Interest cost		2,523,000	2,551,000	5,031,000	5,102,000	10,187,000	10,305,000	94,000	56,000	157,000	111,000	308,000	203,000	922,000	1,032,000	1,913,000	2,065,000	3,885,000	4,257,000
Expected return on plan assets		(3,089,000)	(3,076,000)	(6,214,000)	(6,151,000)	(12,372,000)	(11,721,000)							(1,077,000)	(1,041,000)	(2,176,000)	(2,083,000)	(4,229,000)	(4,161,000)
Amortization of prior service cost		133,000	133,000	266,000	266,000	531,000	532,000	(2,000)	(2,000)	(4,000)	(4,000)	(8,000)	(8,000)	(253,000)	(253,000)	(505,000)	(505,000)	(1,011,000)	(1,011,000)
Amortization of net actuarial loss		2,632,000	1,950,000	5,223,000	3,899,000	9,259,000	6,647,000	180,000	76,000	284,000	153,000	520,000	238,000	481,000	468,000	1,131,000	935,000	1,858,000	1,816,000
Net periodic benefit cost		4,058,000	3,186,000	8,033,000	6,372,000	14,337,000	11,817,000	324,000	137,000	504,000	275,000	924,000	495,000	788,000	771,000	1,833,000	1,541,000	3,245,000	3,163,000
Employer contribution	$ 16,200,000