Energous Corporation Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Tax Cuts and Jobs Act of 2017 Accounting Complete	true
Deferred tax assets, tax credit carryforwards, research	$ 8,371,302	$ 7,390,441
Tax credit carry forward expiration period	2034
Operating loss carryforwards, limitations on use	Stock ownership of one or more 5% stockholders (stockholders owning 5% or more of the Company's outstanding capital stock) has increased on a cumulative basis by more than 50 percentage points.
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 205,474,000
Deferred tax assets, tax credit carryforwards, research	$ 5,092,000
Tax credit research and development expiration period	2033
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 206,403,000
Deferred tax assets, tax credit carryforwards, research	$ 4,151,000