Retirement Benefits (Schedule of Amounts Recognized in Balance Sheet and Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	$ 18,158	$ 2,623
Accrued liabilities	(1,322)	(3)
Other non-current liabilities	(42,631)	(5,407)
Net over/(under)funded status at end of year	(25,795)	(2,787)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	6,459	7,169
Unrecognized net (gains) losses	18,814	31,221
Total amounts recognized	25,273	38,390	$ 58,334
Deferred taxes	(10,973)	(14,240)
Amounts recognized in accumulated other comprehensive loss (income)	14,300	24,150
Other Postretirement Benefit Plans [Member]
Amounts recognized in statement of financial position consist of:
Accrued liabilities	(2,249)	(2,410)
Other non-current liabilities	(25,736)	(29,842)
Net over/(under)funded status at end of year	(27,985)	(32,252)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	(1)	(160)
Unrecognized net (gains) losses	425	3,234
Total amounts recognized	424	3,074	5,166
Deferred taxes	(518)	(1,183)
Amounts recognized in accumulated other comprehensive loss (income)	(94)	1,891
UNITED STATES | Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	17,068	1,726
Other non-current liabilities	(1,758)	(2,524)
Net over/(under)funded status at end of year	15,310	(798)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	6,459	7,169
Unrecognized net (gains) losses	4,285	17,023
Total amounts recognized	10,744	24,192	37,539
Deferred taxes	(5,892)	(9,224)
Amounts recognized in accumulated other comprehensive loss (income)	4,852	14,968
Foreign Plan [Member] | Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	1,090	897
Accrued liabilities	(1,322)	(3)
Other non-current liabilities	(40,873)	(2,883)
Net over/(under)funded status at end of year	(41,105)	(1,989)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net (gains) losses	14,529	14,198
Total amounts recognized	14,529	14,198	$ 20,795
Deferred taxes	(5,081)	(5,016)
Amounts recognized in accumulated other comprehensive loss (income)	$ 9,448	$ 9,182