Supplemental Quarterly Financial Data (Unaudited) (Quarterly Financial Information - Segment Reporting) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Supplemental Quarterly Financial Data [Line Items]
Net sales	$ 606,788	$ 548,622	$ 500,381	$ 442,894	$ 590,922	$ 507,664	$ 479,382	$ 445,110	$ 2,098,685	$ 2,023,078	$ 2,038,303
Interest expense, net	(6,543)	(6,411)	(6,316)	(6,435)	(6,585)	(5,912)	(5,793)	(6,461)	(25,705)	(24,751)	(24,077)
Consolidated earnings before income taxes	86,765	68,687	50,236	47,059	80,756	63,408	54,366	27,956	252,747	226,486	240,949
Aerospace [Member]
Supplemental Quarterly Financial Data [Line Items]
Net sales	399,141	355,992	320,526	266,680	365,305	308,582	290,690	268,599	1,342,339	1,233,176	1,160,883
Segment earnings (loss)	85,536	67,173	58,227	46,877	80,376	57,726	50,578	43,486	257,813	232,166	187,747
Industrial [Member]
Supplemental Quarterly Financial Data [Line Items]
Net sales	207,647	192,630	179,855	176,214	225,617	199,082	188,692	176,511	756,346	789,902	877,420
Segment earnings (loss)	23,034	20,870	17,089	17,998	19,254	21,963	19,469	21,551	78,991	82,237	126,641
Unallocated Corporate [Member]
Supplemental Quarterly Financial Data [Line Items]
Segment earnings (loss)	$ (15,262)	$ (12,945)	$ (18,764)	$ (11,381)	$ (12,289)	$ (10,369)	$ (9,888)	$ (30,620)	$ (58,352)	$ (63,166)	$ (49,362)