Subsequent Events	9 Months Ended
Sep. 30, 2025
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE 10. SUBSEQUENT EVENTS The Company evaluated subsequent events and transactions that occurred after the condensed consolidated balance sheet date up to the date that the unaudited condensed consolidated financial statements were issued. Based upon this review, other than as described below, the Company did not identify any subsequent events that would have required adjustment or disclosure in the unaudited condensed consolidated financial statements. On October 28, 2025, the Company completed its business combination with Terrestrial Energy Inc. (“Terrestrial Energy”), a developer of advanced nuclear power technology. In connection with the closing, the Company changed its name from HCM II Acquisition Corp. to Terrestrial Energy Inc. and its securities began trading on the Nasdaq Stock Market under the symbols “IMSR” and “IMSRW” on October 29, 2025. The transaction generated gross proceeds exceeding $292 million before expenses, including a previously placed $50 million PIPE investment and a negligible level of redemptions by public shareholders. The proceeds are expected to support the Company’s ongoing operations and accelerate the commercial deployment of its proprietary Integral Molten Salt Reactor (IMSR) nuclear technology.

Subsequent Events

9 Months Ended

Sep. 30, 2025

NOTE 10. SUBSEQUENT EVENTS

The Company evaluated subsequent events and transactions that occurred after the condensed consolidated balance sheet date up to the date that the unaudited condensed consolidated financial statements were issued. Based upon this review, other than as described below, the Company did not identify any subsequent events that would have required adjustment or disclosure in the unaudited condensed consolidated financial statements.

On October 28, 2025, the Company completed its business combination with Terrestrial Energy Inc. (“Terrestrial Energy”), a developer of advanced nuclear power technology. In connection with the closing, the Company changed its name from HCM II Acquisition Corp. to Terrestrial Energy Inc. and its securities began trading on the Nasdaq Stock Market under the symbols “IMSR” and “IMSRW” on October 29, 2025. The transaction generated gross proceeds exceeding $292 million before expenses, including a previously placed $50 million PIPE investment and a negligible level of redemptions by public shareholders. The proceeds are expected to support the Company’s ongoing operations and accelerate the commercial deployment of its proprietary Integral Molten Salt Reactor (IMSR) nuclear technology.