Pension and Post-retirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Pension Benefit
Pension and post-retirement benefits
Service cost	$ 1,220	$ 1,000	$ 2,440	$ 2,001
Interest cost	2,657	2,872	5,195	5,548
Expected return	(3,243)	(2,899)	(6,362)	(5,565)
Amortizations	2,749	2,475	5,472	4,923
Net periodic benefit cost	3,383	3,448	6,745	6,907
Domestic pension plans
Pension and post-retirement benefits
Employer contribution			7,500
Expected future employer contribution	7,500		7,500
U.K. pension plan
Pension and post-retirement benefits
Employer contribution			473
Expected future employer contribution	497		497
Other Benefits
Pension and post-retirement benefits
Service cost	97	73	194	146
Interest cost	1,082	1,145	2,164	2,290
Amortizations	(518)	(747)	(1,036)	(1,495)
Net periodic benefit cost	661	471	1,322	941
Employer contribution			2,120
Expected future employer contribution	$ 2,880		$ 2,880