Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024	Apr. 30, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Amortization of deferred contract costs	$ 7,100	$ 1,500		$ 22,700	$ 6,500
Launch delay fees	0	1,000		2,300	2,200
Contract with customer, liability, revenue recognized				40,900	8,400
Net losses related to contracts	1,700	1,700		23,900	22,800
Contract loss provision, current	9,165			9,165			$ 7,890
Contract loss provision	1,636			1,636			0
Revenue, remaining performance obligation, amount	119,300			119,300
Government assistance, award amount						$ 10,000
Government assistance, award, applied to reimburse costs						$ 10,000
Grant revenue	1,450	$ 0		1,450	0
Grants receivable, current	$ 1,500			$ 1,500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period (in months)	3 months			3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01 | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	10.00%			10.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01 | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	15.00%			15.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period (in months)	1 year			1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	55.00%			55.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage	60.00%			60.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period (in months)
IM-1 Mission Contract for Lunar Payload Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with customer, liability, revenue recognized			$ 11,600
Contracts, variable consideration, maximum								$ 12,300
Loss on contracts					5,700
IM-2 Mission Contract for Lunar Payload Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with customer, liability, revenue recognized	$ 5,500
Loss on contracts				$ 1,000	7,200
Contract loss provision, current	$ 0			0			900
IM-3 Mission Contract for Lunar Payload Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Loss on contracts				$ 19,600	$ 9,900
Long-term contract, percent complete	80.00%			80.00%
Contract loss provision, current	$ 7,900			$ 7,900			7,000
Contract loss provision	$ 400			400			$ 0
IM-4 Mission Contract for Lunar Payload Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Loss on contracts				$ 3,300
Long-term contract, percent complete	24.00%			24.00%
Contract loss provision, current	$ 1,300			$ 1,300
Contract loss provision	$ 1,200			$ 1,200