Retirement Benefits (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Benefits
Net Periodic Pension Benefit Cost:
Service cost	$ 1,628,000	$ 1,404,000	$ 3,256,000	$ 2,798,000	$ 6,054,000	$ 5,139,000
Interest cost	2,551,000	2,612,000	5,102,000	5,203,000	10,305,000	10,218,000
Expected return on plan assets	(3,076,000)	(2,889,000)	(6,151,000)	(5,569,000)	(11,721,000)	(10,450,000)
Amortization of prior service cost	133,000	133,000	266,000	266,000	532,000	531,000
Amortization of net actuarial loss	1,950,000	1,395,000	3,899,000	2,747,000	6,647,000	4,676,000
Net periodic benefit cost	3,186,000	2,655,000	6,372,000	5,445,000	11,817,000	10,114,000
Employer contribution			8,100,000
Remaining 2012 employer contribution			3,000,000
SERP
Net Periodic Pension Benefit Cost:
Service cost	7,000	27,000	15,000	47,000	62,000	83,000
Interest cost	56,000	51,000	111,000	91,000	203,000	166,000
Amortization of prior service cost	(2,000)	(2,000)	(4,000)	(4,000)	(8,000)	(8,000)
Amortization of net actuarial loss	76,000	52,000	153,000	85,000	238,000	118,000
Net periodic benefit cost	137,000	128,000	275,000	219,000	495,000	359,000
OPEB
Net Periodic Pension Benefit Cost:
Service cost	565,000	507,000	1,129,000	1,133,000	2,262,000	2,253,000
Interest cost	1,032,000	1,062,000	2,065,000	2,192,000	4,257,000	4,396,000
Expected return on plan assets	(1,041,000)	(1,028,000)	(2,083,000)	(2,078,000)	(4,161,000)	(3,990,000)
Amortization of prior service cost	(253,000)	(253,000)	(505,000)	(505,000)	(1,011,000)	(1,011,000)
Amortization of net actuarial loss	468,000	381,000	935,000	881,000	1,816,000	1,691,000
Net periodic benefit cost	$ 771,000	$ 669,000	$ 1,541,000	$ 1,623,000	$ 3,163,000	$ 3,339,000