Recent Accounting Pronouncements (Schedule of New Accounting Pronouncements) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Total current assets	$ 950,516			$ 950,516		$ 917,710
Noncurrent deferred income tax assets	43,934			43,934		13,105
Total assets	2,646,066			2,646,066		2,513,916
Total current liabilities	451,776			451,776		338,208
Noncurrent deferred income tax liabilities	1,081			1,081		56,414
Total liabilities	1,487,542			1,487,542		1,360,812
Total liabilities and stockholders' equity	2,646,066			2,646,066		2,513,916
Earnings before income taxes	63,408		$ 57,559	145,730	$ 172,222
Income tax expense	12,361		13,806	28,039	40,830
Net earnings	$ 51,047		$ 43,753	$ 117,691	$ 131,392
Basic earnings per share	$ 0.83		$ 0.68	$ 1.90	$ 2.02
Diluted earnings per share	$ 0.81		$ 0.66	$ 1.85	$ 1.98
Basic	61,341		64,781	62,015	65,088
Diluted	63,109		66,227	63,560	66,504
Net cash provided by operating activities				$ 362,481	$ 171,490
Net cash used in investing activities				(122,881)	(188,379)
Net cash provided by (used in) financing activities				(200,635)	(1,466)
Effect of Exchange Rate on Cash and Cash Equivalents				(3,048)	(9,548)
Net change in cash and cash equivalents				$ 35,917	(27,903)
Accounting Standards Update 2016-09 [Member]
Earnings before income taxes		$ 27,956
Income tax expense		2,136
Net earnings		$ 25,820
Basic earnings per share		$ 0.41
Diluted earnings per share		$ 0.40
Basic		63,054
Diluted		64,452
Net cash provided by operating activities		$ 37,360			171,490
Net cash used in investing activities		(31,279)			(188,379)
Net cash provided by (used in) financing activities		(1,379)			(1,466)
Effect of Exchange Rate on Cash and Cash Equivalents		(2,482)			(9,548)
Net change in cash and cash equivalents		2,220			(27,903)
Accounting Standards Update 2016-09 [Member] | Restatement Adjustment [Member]
Earnings before income taxes		0
Income tax expense		(209)
Net earnings		$ 209
Basic earnings per share		$ 0.00
Diluted earnings per share		$ 0.00
Basic		0
Diluted		79
Net cash provided by operating activities		$ 248			4,170
Net cash used in investing activities		0			0
Net cash provided by (used in) financing activities		(248)			(4,170)
Effect of Exchange Rate on Cash and Cash Equivalents		0			0
Net change in cash and cash equivalents		0			0
Accounting Standards Update 2016-09 [Member] | Scenario, Previously Reported [Member]
Earnings before income taxes		27,956
Income tax expense		2,345
Net earnings		$ 25,611
Basic earnings per share		$ 0.41
Diluted earnings per share		$ 0.40
Basic		63,054
Diluted		64,373
Net cash provided by operating activities		$ 37,112			167,320
Net cash used in investing activities		(31,279)			(188,379)
Net cash provided by (used in) financing activities		(1,131)			2,704
Effect of Exchange Rate on Cash and Cash Equivalents		(2,482)			(9,548)
Net change in cash and cash equivalents		$ 2,220			$ (27,903)
Accounting Standards Update 2015-17 [Member]
Current deferred income tax assets						0
Total current assets						917,710
Noncurrent deferred income tax assets						13,105
Total assets						2,513,916
Current deferred income tax liabilities						0
Total current liabilities						338,208
Noncurrent deferred income tax liabilities						56,414
Total liabilities						1,360,812
Total liabilities and stockholders' equity						2,513,916
Net deferred tax liabilities						43,309
Accounting Standards Update 2015-17 [Member] | Restatement Adjustment [Member]
Current deferred income tax assets						(29,766)
Total current assets						(29,766)
Noncurrent deferred income tax assets						3,717
Total assets						(26,049)
Current deferred income tax liabilities						(14)
Total current liabilities						(14)
Noncurrent deferred income tax liabilities						(26,035)
Total liabilities						(26,049)
Total liabilities and stockholders' equity						(26,049)
Net deferred tax liabilities						0
Accounting Standards Update 2015-17 [Member] | Scenario, Previously Reported [Member]
Current deferred income tax assets						29,766
Total current assets						947,476
Noncurrent deferred income tax assets						9,388
Total assets						2,539,965
Current deferred income tax liabilities						14
Total current liabilities						338,222
Noncurrent deferred income tax liabilities						82,449
Total liabilities						1,386,861
Total liabilities and stockholders' equity						2,539,965
Net deferred tax liabilities						$ 43,309