Subsequent Events	3 Months Ended
Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Acquisition of Nesscap Energy, Inc. On April 28, 2017, the Company acquired substantially all of the assets and business of Nesscap Energy, Inc. (“Nesscap”), a developer and manufacturer of ultracapacitor products for use in transportation, renewable energy, industrial and consumer markets, in exchange for the issuance of approximately 4.1 million shares of Maxwell common stock (the “Share Consideration”) and the assumption of certain liabilities pursuant to the terms of the previously announced Arrangement Agreement dated as of February 28, 2017 between Maxwell and Nesscap (the “Acquisition”). The value of the Share Consideration was approximately $25.3 million based on the closing price of the Company’s common stock on April 28, 2017. The Acquisition was effected by means of a court-approved statutory plan of arrangement and was approved by the requisite vote cast by shareholders of Nesscap at a special meeting of Nesscap’s shareholders held on April 24, 2017. The Share Consideration represents approximately 11.3% of the outstanding shares of Maxwell, based on the number of shares of Maxwell common stock outstanding as of April 28, 2017. Since the acquisition date occurred subsequent to March 31, 2017, the Nesscap assets acquired and liabilities assumed are not included in the unaudited condensed consolidated balance sheets as of March 31, 2017. Due to the limited time since the acquisition date, the Company has not had sufficient time to prepare supplemental pro forma information. In addition, the initial purchase accounting for this business combination was incomplete as of the date of filing of this Quarterly Report. SDIC Investment On April 10, 2017, the Company entered into a stock purchase agreement (the “Stock Purchase Agreement”) with SDIC Fund Management Co., Ltd. (the “Investor”), pursuant to which the Company agreed to issue and sell to the Investor 7.4 million shares of the Company’s common stock (the “Shares”) for $6.32 per share, for an aggregate purchase price of approximately $46.6 million (the “Transaction”) to be used for strategic developments, including dry battery electrode development, as well as working capital and general corporate purposes. The Investor’s ownership in the Company’s common stock will be approximately 19.9% of the Company’s total issued and outstanding shares of common stock on a pre-purchase basis as of the closing of the Transaction (the “Closing”), provided, further that the total number of shares purchased by the Investor shall be reduced at the Closing to ensure that any ownership by the Investor will not exceed 19.9% immediately prior to the issuance of the shares to the Investor at the Closing. The Transaction is subject to certain closing conditions, including clearance by the Committee on Foreign Investments in the United States as well as completion of filings with relevant Chinese governmental authorities, and is expected to close in the third quarter of 2017.

Subsequent Events

Acquisition of Nesscap Energy, Inc.

On April 28, 2017, the Company acquired substantially all of the assets and business of Nesscap Energy, Inc. (“Nesscap”), a developer and manufacturer of ultracapacitor products for use in transportation, renewable energy, industrial and consumer markets, in exchange for the issuance of approximately 4.1 million shares of Maxwell common stock (the “Share Consideration”) and the assumption of certain liabilities pursuant to the terms of the previously announced Arrangement Agreement dated as of February 28, 2017 between Maxwell and Nesscap (the “Acquisition”). The value of the Share Consideration was approximately $25.3 million based on the closing price of the Company’s common stock on April 28, 2017. The Acquisition was effected by means of a court-approved statutory plan of arrangement and was approved by the requisite vote cast by shareholders of Nesscap at a special meeting of Nesscap’s shareholders held on April 24, 2017.

The Share Consideration represents approximately 11.3% of the outstanding shares of Maxwell, based on the number of shares of Maxwell common stock outstanding as of April 28, 2017.

Since the acquisition date occurred subsequent to March 31, 2017, the Nesscap assets acquired and liabilities assumed are not included in the unaudited condensed consolidated balance sheets as of March 31, 2017. Due to the limited time since the acquisition date, the Company has not had sufficient time to prepare supplemental pro forma information. In addition, the initial purchase accounting for this business combination was incomplete as of the date of filing of this Quarterly Report.

SDIC Investment

On April 10, 2017, the Company entered into a stock purchase agreement (the “Stock Purchase Agreement”) with SDIC Fund Management Co., Ltd. (the “Investor”), pursuant to which the Company agreed to issue and sell to the Investor 7.4 million shares of the Company’s common stock (the “Shares”) for $6.32 per share, for an aggregate purchase price of approximately $46.6 million (the “Transaction”) to be used for strategic developments, including dry battery electrode development, as well as working capital and general corporate purposes. The Investor’s ownership in the Company’s common stock will be approximately 19.9% of the Company’s total issued and outstanding shares of common stock on a pre-purchase basis as of the closing of the Transaction (the “Closing”), provided, further that the total number of shares purchased by the Investor shall be reduced at the Closing to ensure that any ownership by the Investor will not exceed 19.9% immediately prior to the issuance of the shares to the Investor at the Closing.

The Transaction is subject to certain closing conditions, including clearance by the Committee on Foreign Investments in the United States as well as completion of filings with relevant Chinese governmental authorities, and is expected to close in the third quarter of 2017.