Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net, Current	$ 20,700								$ 20,700
Professional services and hosting									1,044,670
Product and licensing									509,226		$ 544,019		$ 493,911
Maintenance and support									269,196		252,557		267,698
Revenues	470,658	$ 449,197	$ 409,583	$ 493,654	$ 479,432	$ 449,449	$ 466,193	$ 447,224	1,823,092	[1]	$ 1,842,298	[1]	$ 1,728,175	[1]
Capitalized Contract Cost, Net, Noncurrent	$ 31,100								31,100
Healthcare
Disaggregation of Revenue [Line Items]
Professional services and hosting									546,037
Product and licensing									246,788
Maintenance and support									156,905
Revenues									949,730
Enterprise
Disaggregation of Revenue [Line Items]
Professional services and hosting									316,247
Product and licensing									82,073
Maintenance and support									111,758
Revenues									510,078
Automotive
Disaggregation of Revenue [Line Items]
Professional services and hosting									131,027
Product and licensing									170,532
Maintenance and support									262
Revenues									301,821
Other Mobile Businesses [Member]
Disaggregation of Revenue [Line Items]
Professional services and hosting									51,359
Product and licensing									9,833
Maintenance and support									271
Revenues									$ 61,463

[1] Segment revenues differ from reported revenues due to certain revenue adjustments related to acquisitions that would otherwise have been recognized but for the purchase accounting treatment of the business combinations. These revenues are included to allow for more complete comparisons to the financial results of historical operations and in evaluating management performance.