Pension Plan and Retirement Benefits - Benefit Obligation Assumptions (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2007	Sep. 30, 2016	Sep. 30, 2015
U.S. pension plan
Assumptions used to determine benefit obligation
Discount rate (as a percent)		3.25%	4.00%
Rate of compensation increase (as a percent)		3.50%	3.50%
U.K. pension plan
Assumptions used to determine benefit obligation
Discount rate (as a percent)		2.30%	3.70%
Postretirement Health Care Benefits
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)		5.00%
Effect of one percentage point change in assumed health care cost trend rates
Effect on total of service and interest cost components of one percent increase		$ 0
Effect on total of service and interest cost components of one percent decrease		0
Effect on accumulated postretirement benefit obligation of one percent increase		0
Effect on accumulated postretirement benefit obligation of one percent decrease		$ 0
Maximum liability related to total retiree health care costs under plan amendment	$ 5,000
Assumptions used to determine benefit obligation
Discount rate (as a percent)		3.50%	4.25%
Postretirement Health Care Benefits | Minimum
Assumptions relating to health care cost trend rates
Employee age required to participate in the plan		65 years
Postretirement Health Care Benefits | Maximum
Assumptions relating to health care cost trend rates
Employee age required to participate in the plan		65 years
Postretirement Health Care Benefits | Under 65 age group
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)		5.00%	5.00%
Postretirement Health Care Benefits | Over 65 age group
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)		5.00%	5.00%