Supplemental Quarterly Financial Data (Unaudited) (Quarterly Financial Information - Segment Reporting) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Supplemental Quarterly Financial Data [Line Items]
Net sales	$ 719,359	$ 588,117	$ 548,249	$ 470,148	$ 606,788	$ 548,622	$ 500,381	$ 442,894	$ 2,325,873	$ 2,098,685	$ 2,023,078
Interest expense, net	(9,957)	(7,536)	(6,216)	(6,387)	(6,543)	(6,411)	(6,316)	(6,435)	(30,096)	(25,705)	(24,751)
Consolidated earnings before income taxes	79,027	54,417	48,647	37,487	86,765	68,687	50,236	47,059	219,578	252,747	226,486
Aerospace [Member]
Supplemental Quarterly Financial Data [Line Items]
Net sales	461,128	404,612	386,343	305,905	399,141	355,992	320,526	266,680	1,557,988	1,342,339	1,233,176
Segment earnings (loss)	103,082	82,199	72,969	43,553	85,536	67,173	58,227	46,877	301,803	257,813	232,166
Industrial [Member]
Supplemental Quarterly Financial Data [Line Items]
Net sales	258,231	183,505	161,906	164,243	207,647	192,630	179,855	176,214	767,885	756,346	789,902
Segment earnings (loss)	7,907	10,450	10,237	19,344	23,034	20,870	17,089	17,998	47,938	78,991	82,237
Unallocated Corporate [Member]
Supplemental Quarterly Financial Data [Line Items]
Segment earnings (loss)	$ (22,005)	$ (30,696)	$ (28,343)	$ (19,023)	$ (15,262)	$ (12,945)	$ (18,764)	$ (11,381)	$ (100,067)	$ (58,352)	$ (63,166)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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