Retirement Benefits (Schedule of Amounts Recognized in Balance Sheet and Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	$ 2,623	$ 0
Accrued liabilities	(3)	0
Other non-current liabilities	(5,407)	(24,137)
Net over/(under)funded status at end of year	(2,787)	(24,137)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	7,169	3,857
Unrecognized net (gains) losses	31,221	54,477
Total amounts recognized	38,390	58,334	$ 44,720
Deferred taxes	(14,240)	(21,608)
Amounts recognized in accumulated other comprehensive loss (income)	24,150	36,726
Other Postretirement Benefit Plans [Member]
Amounts recognized in statement of financial position consist of:
Accrued liabilities	(2,410)	(2,505)
Other non-current liabilities	(29,842)	(33,125)
Net over/(under)funded status at end of year	(32,252)	(35,630)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	(160)	(318)
Unrecognized net (gains) losses	3,234	5,484
Total amounts recognized	3,074	5,166	3,268
Deferred taxes	(1,183)	(1,979)
Amounts recognized in accumulated other comprehensive loss (income)	1,891	3,187
UNITED STATES | Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	1,726	0
Accrued liabilities	0	0
Other non-current liabilities	(2,524)	(15,006)
Net over/(under)funded status at end of year	(798)	(15,006)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	7,169	3,857
Unrecognized net (gains) losses	17,023	33,682
Total amounts recognized	24,192	37,539	31,102
Deferred taxes	(9,224)	(14,305)
Amounts recognized in accumulated other comprehensive loss (income)	14,968	23,234
Foreign Plan [Member] | Defined Benefit Pension Plan [Member]
Amounts recognized in statement of financial position consist of:
Other non-current assets	897	0
Accrued liabilities	(3)	0
Other non-current liabilities	(2,883)	(9,131)
Net over/(under)funded status at end of year	(1,989)	(9,131)
Amounts recognized in accumulated other comprehensive loss (income) consist of:
Unrecognized net prior service (benefit) cost	0	0
Unrecognized net (gains) losses	14,198	20,795
Total amounts recognized	14,198	20,795	$ 13,618
Deferred taxes	(5,016)	(7,303)
Amounts recognized in accumulated other comprehensive loss (income)	$ 9,182	$ 13,492