Balance Sheet Information - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Sep. 30, 2021	Jul. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Feb. 28, 2022
Condensed Balance Sheet Statements Captions [Line Items]
Asset impairment			$ 54,343,000	$ 171,824,000
Depreciation expense			60,200,000	80,500,000	$ 81,200,000
Estimated initial equity warrant asset value			16,400,000
Warrant asset value			16,400,000
Investments in equity securities			20,320,000	15,178,000
Estimated initial warrant asset value						$ 3,200,000
Net gains/(losses) on investments in equity securities			5,400,000	(13,700,000)
Aggregate carrying amount of investments in equity securities			20,300,000
Investments without readily determinable fair value			8,800,000
Level 3 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Investments in equity securities			3,500,000
Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Gains/(losses) on investments			5,600,000	(13,700,000)
Archer Aviation, Inc. [Member] | Level 1 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Investments in equity securities			11,500,000
Heart Aerospace Incorporated [Member] | Level 3 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Investments in equity securities			5,000,000
Heart Aerospace Incorporated [Member] | Forward Purchase Contract [Member] | Preferred Stock [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Purchase of preferred stock		$ 5,000,000
Initial investment in preferred stock measured at cost		$ 5,000,000
Class A [Member] | Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Stock issued during period, Shares	500,000
Stock issued during period, Value	$ 5,000,000
Total grant date value, Additional warrant to purchase shares	$ 5,600,000
Long Lived Assets [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Asset impairment			0
CRJ-900 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Asset impairment			0
CRJ-900 [Member] | Long Lived Assets [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Asset impairment			$ 0	$ 116,600,000	$ 0