Selected Financial Data for the Three Months Ended December 31, 2017 (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Results of Operations
Grant income	$ 296	$ 231	$ 1,407	$ 1,693	$ 1,212
Operating expenses:
Research and development	(17,713)	(5,564)	(36,150)	(16,012)	(10,436)
General and administrative	(7,593)	(3,084)	(22,790)	(9,099)	(5,152)
Total operating expenses, net	(25,010)	(8,417)	(57,533)	(23,418)	(14,376)
Other income (expense):
Interest income	660	181	1,532	84	75
Other income (expense)	1,097	(685)	3,970	(46)	(26)
Total other income, net	1,757	(504)	5,502	38	49
Net loss before income tax	(23,253)	(8,921)	(52,031)	(23,380)	(14,327)
Income tax benefit	2,605	1,397	7,280	3,653	1,777
Net loss attributable to ordinary shareholders	(20,648)	(7,524)	(44,751)	(19,727)	(12,550)
Cash Flows
Net cash used in operating activities	(19,785)	(8,797)	(31,537)	(16,360)	(9,849)
Net cash used in investing activities	(4,422)	(764)	(9,531)	(2,876)	(1,855)
Net cash provided by financing activities	0	433	156,920	127,686	32,222
Effect of exchange rate changes on cash		1,042
Net decrease in cash		(8,086)
Balance Sheet Data
Cash	217,450	128,984	246,984	137,070	28,059
Working capital		131,576
Net assets		137,515
Total assets	254,210	142,715	273,205	148,662
Ordinary shares		1
Additional paid-in capital	361,311	195,644	357,918	194,351
Total shareholders' equity	$ 232,642	$ 137,515	$ 255,465	$ 142,601	$ 30,687	$ 10,501

Working Capital

No definition available.

Name:	autl_WorkingCapital
Namespace Prefix:	autl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682