Related Party Transactions	12 Months Ended
Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Weichai Transactions See Note 3. Weichai Transactions for information regarding the Weichai SPA and Collaboration Agreement. Transactions with Joint Ventures MAT-PSI Holdings, LLC In December 2012, the Company and MAT Holdings, Inc. (“MAT”) entered into an agreement to create MAT-PSI Holdings, LLC (“MAT-PSI”), which was intended to be a holding company of its 100% Chinese wholly-owned foreign entity, referred to as Green Power. The Company invested $0.9 million for its 50% share of MAT-PSI, which was formed to manufacture, assemble and supply natural gas, gas and alternative-fueled power systems to Chinese and Asian forklift customers. The venture established a production facility in Dalian and also sourced base engines from a local Chinese factory. As MAT-PSI was not profitable, the venture was closed in 2017. The Company’s investment was accounted for under the equity method of accounting. Doosan-PSI, LLC In 2015, the Company and Doosan Infracore Co., Ltd. (“Doosan”), a subsidiary of Doosan Group, entered into an agreement to form Doosan-PSI, LLC. The Company invested $1.0 million to acquire 50% of the venture, which was formed to operate in the field of developing, designing, testing, manufacturing, assembling, branding, marketing, selling, distributing and providing support for industrial gas engines and all components and materials required for assembly of the gas engines to the global power generation market outside of North America and South Korea. Sterling and Wilson Cogen Solutions, LLC On April 13, 2016, the Company and Sterling and Wilson Power Systems Inc. (“SW”) entered into an agreement for the formation and operation of Sterling and Wilson Cogen Solutions, LLC. The Company invested $0.2 million for its 49% share of the venture. Effective May 31, 2017, the Company sold its 49% membership interest in the venture to SW for $0.2 million pursuant to the agreement. Joint Venture Operating Results The Company’s investments in joint ventures are accounted for under the equity method of accounting. The Company's Consolidated Statement of Operations included a gain from these investments of $0.2 million in 2018. In 2017, the gain was immaterial. The joint venture operating results are presented in Other expense (income), net in the Company’s Consolidated Statements of Operations. Transactions with Related Individuals William D. Winemaster William D. Winemaster, the father of Gary S. Winemaster, former Chairman of the Board, Chief Executive Officer and President and nonexecutive Chief Strategy Officer, and Kenneth J. Winemaster, Executive Vice President, served as an employee performing consulting and advisory-type services, for which he was paid a salary, an amount for automobiles and related insurance premiums, mobile-telephone services and a bonus. The Company paid to William D. Winemaster $0.2 million in 2017. Additionally, in 2018, William D. Winemaster retired and for his service was awarded a $0.1 million founders award. Industrial Electronic Controls The Company purchased $0.4 million of products in 2018 from Industrial Electronic Controls, a supplier of custom throttles, sensors, and custom electronics. Gary S. Winemaster, former Chairman of the Board, Chief Executive Officer and President and non-executive Chief Strategy Officer owned 50% of Industrial Electronic Controls during 2018.

Related Party Transactions

Weichai Transactions

See Note 3. Weichai Transactions for information regarding the Weichai SPA and Collaboration Agreement.

Transactions with Joint Ventures

MAT-PSI Holdings, LLC

In December 2012, the Company and MAT Holdings, Inc. (“MAT”) entered into an agreement to create MAT-PSI Holdings, LLC (“MAT-PSI”), which was intended to be a holding company of its 100% Chinese wholly-owned foreign entity, referred to as Green Power. The Company invested $0.9 million for its 50% share of MAT-PSI, which was formed to manufacture, assemble and supply natural gas, gas and alternative-fueled power systems to Chinese and Asian forklift customers. The venture established a production facility in Dalian and also sourced base engines from a local Chinese factory. As MAT-PSI was not profitable, the venture was closed in 2017. The Company’s investment was accounted for under the equity method of accounting.

Doosan-PSI, LLC

In 2015, the Company and Doosan Infracore Co., Ltd. (“Doosan”), a subsidiary of Doosan Group, entered into an agreement to form Doosan-PSI, LLC. The Company invested $1.0 million to acquire 50% of the venture, which was formed to operate in the field of developing, designing, testing, manufacturing, assembling, branding, marketing, selling, distributing and providing support for industrial gas engines and all components and materials required for assembly of the gas engines to the global power generation market outside of North America and South Korea.

Sterling and Wilson Cogen Solutions, LLC

On April 13, 2016, the Company and Sterling and Wilson Power Systems Inc. (“SW”) entered into an agreement for the formation and operation of Sterling and Wilson Cogen Solutions, LLC. The Company invested $0.2 million for its 49% share of the venture. Effective May 31, 2017, the Company sold its 49% membership interest in the venture to SW for $0.2 million pursuant to the agreement.

Joint Venture Operating Results

The Company’s investments in joint ventures are accounted for under the equity method of accounting. The Company's Consolidated Statement of Operations included a gain from these investments of $0.2 million in 2018. In 2017, the gain was immaterial. The joint venture operating results are presented in Other expense (income), net in the Company’s Consolidated Statements of Operations.

Transactions with Related Individuals

William D. Winemaster

William D. Winemaster, the father of Gary S. Winemaster, former Chairman of the Board, Chief Executive Officer and President and nonexecutive Chief Strategy Officer, and Kenneth J. Winemaster, Executive Vice President, served as an employee performing consulting and advisory-type services, for which he was paid a salary, an amount for automobiles and related insurance premiums, mobile-telephone services and a bonus. The Company paid to William D. Winemaster $0.2 million in 2017. Additionally, in 2018, William D. Winemaster retired and for his service was awarded a $0.1 million founders award.

Industrial Electronic Controls

The Company purchased $0.4 million of products in 2018 from Industrial Electronic Controls, a supplier of custom throttles, sensors, and custom electronics. Gary S. Winemaster, former Chairman of the Board, Chief Executive Officer and President and non-executive Chief Strategy Officer owned 50% of Industrial Electronic Controls during 2018.