Pension Benefit and Other Postretirement Benefit Plans (Additional Information) (Details) (USD $)	3 Months Ended		4 Months Ended	9 Months Ended			3 Months Ended				6 Months Ended	9 Months Ended		3 Months Ended			6 Months Ended			9 Months Ended		4 Months Ended			12 Months Ended	4 Months Ended		4 Months Ended						3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Apr. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Jun. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2012 Retirement Health and Life Insurance Benefits [Member]	Mar. 31, 2012 Retirement Health and Life Insurance Benefits [Member]	Jun. 30, 2012 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2012 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2013 Pension Benefits [Member]	Jun. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Jun. 30, 2013 Pension Benefits [Member]		Jun. 30, 2012 Pension Benefits [Member]	Sep. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Apr. 30, 2013 Equity Securities [Member]	Apr. 30, 2013 Debt Securities [Member]	Apr. 30, 2013 Hypothetical rates of return on plan assets for a 10 year period [Member]	Dec. 31, 2012 Hypothetical rates of return on plan assets for a 10 year period [Member]	Apr. 30, 2013 Hypothetical rates of return on plan assets for a 15 year period [Member]	Apr. 30, 2013 Historical performance of plan assets over a 16 year period [Member]	Apr. 30, 2013 Hypothetical rates of return on plan assets for a 20 year period [Member]	Apr. 30, 2013 Hypothetical rates of return on plan assets for a 30 year period [Member]	Apr. 30, 2013 Fixed Income Securities [Member] Hypothetical rates of return on plan assets for a 10 year period [Member]	Apr. 30, 2013 Fixed Income Securities [Member] Hypothetical rates of return on plan assets for a 15 year period [Member]	Apr. 30, 2013 Equity Securities [Member] Hypothetical rates of return on plan assets for a 10 year period [Member]	Apr. 30, 2013 Equity Securities [Member] Hypothetical rates of return on plan assets for a 15 year period [Member]	Sep. 30, 2012 Former President and Chief Executive Officer [Member] Pension Benefits [Member]	Sep. 30, 2012 Former President and Chief Executive Officer [Member] Pension Benefits [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Projected benefit obligation of plan assets with accumulated benefit obligation in excess of plan assets						$ 191,400,000
Accumulated benefit obligation of plan assets with accumulated benefit obligation in excess of plan assets						191,400,000
Fair value of plan assets with accumulated benefit obligation in excess of plan assets						157,400,000
Special termination benefit								(700,000)	0	2,300,000	1,593,000		1,593,000				0	[1]
Benefit payments																	3,642,000	[1]																	6,300,000
Settlement charge																2,023,000					2,023,000													2,000,000
Curtailment charge															1,537,000					1,537,000
Target plan asset allocations (percent)			8.60%																			57.00%	43.00%	8.00%	7.30%	7.80%		8.10%	10.20%	3.50%	4.50%	9.50%	11.00%
Number of Years (years)																								10 years		15 years	16 years	20 years	30 years
Employer voluntary contributions	$ 0	$ 6,300,000		$ 0	$ 6,300,000												$ 6,500,000	[1]	$ 16,000,000	$ 13,000,000

[1] This calculation was performed as of June 30, 2013 due to the pension freeze and we are not otherwise required to perform the calculation at interim periods