Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended				6 Months Ended	12 Months Ended
	Feb. 27, 2026 USD ($) $ / shares shares	Jan. 13, 2026 USD ($) $ / shares shares	Mar. 31, 2026 USD ($) reportableSegment operatingSegment $ / shares	Mar. 31, 2026 USD ($) $ / shares	Dec. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2026 USD ($) $ / shares	Dec. 31, 2025 USD ($)	Oct. 01, 2025 $ / shares
Property, Plant and Equipment [Line Items]
Number of operating segments | operatingSegment			1
Number of reportable segments | reportableSegment			1
Orbital receivables, sales, maximum term			5 years
Business combination, transaction costs			$ 20,000
Payments of stock issuance costs			7,550			$ 0
Warranty and after-sale service cost, liability		$ 13,300	11,700	$ 11,700			$ 11,700
Warranty and after-sale service costs, decrease for payments and use				1,600
Cash and cash equivalents			231,624	231,624	$ 582,606	$ 373,253	231,624	$ 582,606
Working capital surplus (deficit)			$ 89,800	$ 89,800			$ 89,800
Share price (in dollars per share) | $ / shares		$ 17.57							$ 10.61
Class A Common Stock
Property, Plant and Equipment [Line Items]
Share price (in dollars per share) | $ / shares			$ 18.56	$ 18.56			$ 18.56		$ 10.61
Class A Common Stock | Securities Purchase Agreement
Property, Plant and Equipment [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares	11,574,069
Sale of stock, price per share (in dollars per share) | $ / shares	$ 15.12
Sale of stock, consideration received on transaction	$ 175,000
Lanteris Space Holdings LLC
Property, Plant and Equipment [Line Items]
Business combination, transaction costs			$ 19,000		$ 10,400		$ 29,400
Voting equity interest acquired, percentage		100.00%
Purchase consideration		$ 850,982
Cash consideration		403,340
Transaction bonuses and other adjustments		$ 43,689
Equity interest issued or issuable (in shares) | shares		22,991,028
Fair value of Class A Common Stock issued		$ 403,953
Cost of Goods and Service Benchmark | Supplier Concentration Risk | One Major Supplier
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			11.00%
Accounts Payable Benchmark | Supplier Concentration Risk | One Major Supplier
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			19.00%					11.00%
One Major Customer | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage						78.00%
Customer One | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			36.00%
Customer One | Accounts Receivable Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			37.00%					49.00%
Customer Two | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			26.00%
Customer Two | Accounts Receivable Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			12.00%					23.00%
Customer Three | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			13.00%
Customer Three | Accounts Receivable Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			19.00%					11.00%
Customer Four | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			13.00%
Customer Four | Accounts Receivable Benchmark | Customer Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk, percentage			14.00%