Pension Benefit and Retirement Health and Life Insurance Benefits (Obligations and Funded Status) (Details) (USD $)	3 Months Ended			12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit payments		$ (6,300,000)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer contributions				2,100,000	1,700,000	1,700,000
Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year				209,844,000	193,715,000
Service cost				2,473,000	4,596,000	3,922,000
Interest cost				7,753,000	8,420,000	8,535,000
Actuarial (gain) loss				(15,834,000)	16,636,000
Benefit payments				(7,276,000)	(6,800,000)
Settlement charge		(2,100,000)		0	(6,723,000)
Special termination benefit				(22,635,000)	0
Benefit obligation at end of year	209,844,000			174,325,000	209,844,000	193,715,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year				143,540,000	120,565,000
Actual return on plan assets				21,954,000	13,775,000
Employer contributions	0		0	13,000,000	22,723,000
Fair value of plan assets at the end of the year	143,540,000			171,218,000	143,540,000	120,565,000
Funded status	(66,304,000)			(3,107,000)	(66,304,000)
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year				11,891,000	10,495,000
Service cost				627,000	630,000	693,000
Interest cost				262,000	364,000	413,000
Actuarial (gain) loss				(1,205,000)	(395,000)
Benefit payments				(751,000)	(795,000)
Settlement charge				0	0
Special termination benefit				0	1,592,000
Benefit obligation at end of year	11,891,000			10,824,000	11,891,000	10,495,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at the beginning of the year				0	0
Actual return on plan assets				0	0
Employer contributions				751,000	795,000
Fair value of plan assets at the end of the year	0			0	0	0
Funded status	$ (11,891,000)			$ (10,824,000)	$ (11,891,000)