v3.20.1

Quarterly Results (unaudited) - Summary of Unaudited Quarterly Results (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
License revenue, and other					$ 2,144	$ 18,821,953	$ 1,333,333			$ 20,157,430
Type of Revenue [Extensible List]					arpo:LicenseRevenueAndOtherMember	arpo:LicenseRevenueAndOtherMember	arpo:LicenseRevenueAndOtherMember	arpo:LicenseRevenueAndOtherMember		arpo:LicenseRevenueAndOtherMember
Total operating expenses	$ 4,657,232	$ 4,966,638	$ 5,978,919	$ 8,841,293	$ 8,868,322	$ 7,623,916	$ 7,369,788	$ 7,476,648	$ 24,444,082	$ 31,338,674
Loss from operations	(4,657,232)	(4,966,638)	(5,978,919)	(8,841,293)	(8,866,178)	11,198,037	(6,036,455)	(7,476,648)	(24,444,082)	(11,181,244)
Other income	211,089	318,708	295,303	348,468	347,588	339,441	46,464	51,116	1,173,568	784,609
Net and comprehensive (loss) income attributable to common stockholders	$ (4,446,143)	$ (4,647,930)	$ (5,683,616)	$ (8,492,825)	$ (8,518,590)	$ 11,537,478	$ (5,989,991)	$ (7,425,532)	$ (23,270,514)	$ (10,396,635)
Basic and diluted	$ (0.11)	$ (0.11)	$ (0.14)	$ (0.21)	$ (0.21)	$ 0.28	$ (0.22)	$ (0.27)	$ (0.57)	$ (0.31)
Weighted average number of common shares used in computing net and comprehensive (loss) income per share:
Basic					40,587,928	40,527,722	27,340,914	27,045,509
Diluted					40,587,928	40,961,620	27,340,914	27,045,509
Basic and diluted	40,588,004	40,588,004	40,588,004	40,588,004					40,588,004	33,930,846

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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