New accounting standards (Tables)

12 Months Ended

Sep. 30, 2016

Accounting Standards Updates 2015-03, 2015-15 and 2015-17 [Member]

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

	September 30, 2015
	As previously reported		Adjustment for ASU 2015-17		Adjustment for ASU 2015-03		As recast
Current deferred income tax assets	$	29,766	$	(29,766)	$	-	$	-
Other current assets		43,791		-		(291)		43,500
Total current assets		947,476		(29,766)		(291)		917,419
Noncurrent deferred income tax assets		9,388		3,717		-		13,105
Other assets		44,886		-		(1,221)		43,665
Total assets		2,539,965		(26,049)		(1,512)		2,512,404
Current deferred income tax liabilities		14		(14)		-		-
Total current liabilities		338,222		(14)		-		338,208
Long-term debt, less current portion		850,000		-		(1,512)		848,488
Noncurrent deferred income tax liabilities		82,449		(26,035)		-		56,414
Total liabilities		1,386,861		(26,049)		(1,512)		1,359,300
Total liabilities and stockholders' equity		2,539,965		(26,049)		(1,512)		2,512,404
Net deferred tax liabilities		43,309		-		-		43,309

Accounting Standards Update 2016-09 [Member]

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

The following table shows the impact of retrospectively applying this guidance to the Condensed Consolidated Statement of Earnings and Condensed Consolidated Statement of Cash Flows for the three-months ended December 31, 2015.

	Three-Months Ended December 31, 2015
	As previously reported		Adjustment		As recast
Statement of Earnings:
Earnings before income taxes	$	27,956	$	-	$	27,956
Income tax expense		2,345		(209)		2,136
Net earnings	$	25,611	$	209	$	25,820
Earnings per share:
Basic earnings per share	$	0.41	$	-	$	0.41
Diluted earnings per share	$	0.40	$	-	$	0.40
Weighted average common shares outstanding:
Basic		63,054		-		63,054
Diluted		64,373		79		64,452
Statement of Cash Flows:
Net cash provided by operating activities	$	37,112	$	248	$	37,360
Net cash used in investing activities		(31,279)		-		(31,279)
Net cash used in financing activities		(1,131)		(248)		(1,379)
Effect of exchange rate changes on cash and cash equivalents		(2,482)		-		(2,482)
Net change in cash and cash equivalents	$	2,220	$	-	$	2,220

The following tables shows the impact of retrospectively applying this guidance to the Consolidated Statements of Cash Flows for the fiscal years ended September 30, 2015 and September 30, 2014.

	Fiscal Year Ended September 30, 2015
	As previously reported		Adjustment		As recast
Statement of Cash Flows:
Net cash provided by operating activities	$	287,429	$	8,561	$	295,990
Net cash used in investing activities		(284,083)		-		(284,083)
Net cash used in financing activities		(25,445)		(8,561)		(34,006)
Effect of exchange rate changes on cash and cash equivalents		(10,986)		-		(10,986)
Net change in cash and cash equivalents	$	(33,085)	$	-	$	(33,085)

	Fiscal Year Ended September 30, 2014
	As previously reported		Adjustment		As recast
Statement of Cash Flows:
Net cash provided by operating activities	$	268,083	$	5,487	$	273,570
Net cash used in investing activities		(205,829)		-		(205,829)
Net cash provided by (used in) financing activities		9,477		(5,487)		3,990
Effect of exchange rate changes on cash and cash equivalents		(5,000)		-		(5,000)
Net change in cash and cash equivalents	$	66,731	$	-	$	66,731