Common Stock - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended							3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 31, 2022 USD ($) shares	Jul. 28, 2022	Jun. 30, 2022 USD ($) $ / shares shares	May 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($)	Feb. 28, 2021 USD ($) $ / shares shares	Mar. 31, 2022 USD ($)	Jun. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Feb. 08, 2022	Jun. 21, 2021 shares	Feb. 13, 2021 shares
Class of Stock [Line Items]
Common Stock, Shares Authorized | shares			300,000,000		80,071,901				300,000,000
Preferred Stock, Shares Authorized | shares			10,000,000						10,000,000
Stock Issued During Period, Shares, New Issues | shares									83,412,347
Proceeds From Share Subscription Facility Provided By Business Acquired									$ 125,000
Common Stock, Shares, Outstanding | shares			129,613,549		57,020,151				129,613,549
Class of Warrant or Right, Outstanding | shares			30,003,547						30,003,547
Proceeds From Convertible Debt									$ 0	$ 37,130
Adjustments to Additional Paid in Capital, Warrant Issued								$ 17,602
Percentage of average trading price to determine other values.			90.00%
Short-term debt			$ 0		$ 34,311				$ 0
The Extension Notes [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares							6,298,306
Proceeds From Convertible Debt							$ 48,700
Public Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding | shares			13,799,988						13,799,988
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 11.50						$ 11.50
Number of trading days for determining the share price									20 days
Number of consecutive trading days for determining the share price									30 days
Share Price | $ / shares			18.00						$ 18.00
Public Warrants [Member] | Share Price Equal or Exceeds Eighteen Rupees Per Dollar [Member]
Class of Stock [Line Items]
Share Price | $ / shares			$ 18.00						18.00
Class of warrants redemption price per unit | $ / shares									$ 0.01
Private Placement Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding | shares			7,520,000						7,520,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 11.50						$ 11.50
Two Thousand And Twenty Three Notes Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding | shares			5,285,636						5,285,636
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 0.01						$ 0.01
Class of warrants and rights issued during the period | shares											3,527,241
Class of warrants and rights issued price per warrant | $ / shares							$ 0.01				$ 0.01
Proceeds from Issuance of Private Placement											$ 16,100
Warrants and rights outstanding, expire period							March 2025				March 2025
Proceeds allocated to the common stock warrants							$ 22,000				$ 7,200
Sensata Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding | shares													2,500,000
Adjustments to Additional Paid in Capital, Warrant Issued						$ 17,600
Warrants exercised for cash						25
Sensata Warrants [Member] | Prepaid Expenses and Other Current Assets [Member]
Class of Stock [Line Items]
Sensata prepaid services						8,800				8,800
Sensata Warrants [Member] | Other Noncurrent Assets [Member]
Class of Stock [Line Items]
Sensata prepaid services						$ 8,800				$ 8,800
GEM Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding | shares			3,397,923						3,397,923
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 10.00		$ 10.00				$ 10.00
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares					3,397,923
GEM Agreement [Member]
Class of Stock [Line Items]
Percentage Price Used For Determining Average Closing Price					90
Proceeds From Share Subscription Facility Provided By Business Acquired					$ 125,000
Warrants Fair Value Disclosure			$ 4,000						$ 4,000
Warrants Payable In Cash									2,500
Unamortized deferred offering costs			2,300						2,300
Line Of Credit commitment fee									2,500
Warrants issued									4,000
Asset Fair Value			1,100						1,100
Number of trading days for determining the share price				30 days
Draw down amount on GEM Agreement				$ 9,900
Shares issued upon draw down of GEM agreement | shares				26,283,186
Expense for the change in fair value of the forward asset			$ 8,900						$ 8,900
Share Settled Forward Asset	$ 10,000
Percentage of average trading price to determine other values.				90.00%
Common stock, shares returned upon settlement | shares	1,134,581
Warrant exercisable , percent									2.50%
Except Series B And Series C Convertible Preferred Stock (Legacy Quanergy) [Member]
Class of Stock [Line Items]
Common Stock Convertible Conversion Ratio			3.8799						3.8799
Series B Convertible Preferred Stock (Legacy Quanergy) [Member]
Class of Stock [Line Items]
Common Stock Convertible Conversion Ratio			11.5423						11.5423			11.5423
Series C Convertible Preferred Stock (Legacy Quanergy) [Member]
Class of Stock [Line Items]
Common Stock Convertible Conversion Ratio			14.3118						14.3118			14.3118
Common Class A [Member] | Prior to Business Combination [Member]
Class of Stock [Line Items]
Common Stock, Shares, Outstanding | shares			27,600,000						27,600,000					27,600,000
Subsequent Event [Member] | GEM Agreement [Member]
Class of Stock [Line Items]
Number of consecutive trading days for determining the share price	40 days	30 days
Maximum [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized | shares			310,000,000						310,000,000