Merger (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 15, 2021 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Subsidiary, Sale of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion | shares		61,468		61,468
Reverse recapitalization transaction		$ 101,035
Proceeds from reverse recapitalization and PIPE financing	$ 133,663			$ 133,663	$ 0
Payments for cash payout of stock options as a result of the Merger				22,806
Additional Paid in Capital		196,330		196,330		$ 3,707
Deferred transaction costs				11,836
Cash payout of options during merger				9,890	0
General and Administrative Expense		$ 9,250	$ 3,173	$ 22,516	$ 8,593
Number of shares vested | shares	496,717
Consideration received	$ 9,890
Numbers shares subject to vesting | shares		2,807,500		2,807,500
Assumed current assets and liabilities		$ 66		$ 66
Gross proceeds from merger				145,499
General and Administrative Expense [Member]
Subsidiary, Sale of Stock [Line Items]
Deferred transaction costs				5,370
Additional Paid-in Capital [Member]
Subsidiary, Sale of Stock [Line Items]
Reverse recapitalization transaction	101,033	101,033
Minimum [Member]
Subsidiary, Sale of Stock [Line Items]
Deferred transaction costs				11,836
Sandbridge [Member]
Subsidiary, Sale of Stock [Line Items]
General and Administrative Expense		$ 1,279		$ 5,306
Sale of stock, consideration received	$ 197,588
Sale of stock, price per share | $ / shares	$ 10.00
Number of shares subject to forfeiture (in shares) | shares		2,807,500		2,807,500
Numbers shares subject to vesting | shares		2,807,500		2,807,500
Transaction cost	$ 17,206
Gross proceeds from initial public offering				$ 213,407
Redemption of stock, cash paid				$ 197,588
Common Class A [Member] | Sandbridge [Member]
Subsidiary, Sale of Stock [Line Items]
Stock redeemed or called during period, shares | shares	19,758,773
Stock Issued During Period, Shares, Conversion of Convertible Securities | shares	3,241,227
Common Class B [Member] | Sandbridge [Member]
Subsidiary, Sale of Stock [Line Items]
Number of shares subject to forfeiture (in shares) | shares	2,807,500
Numbers shares subject to vesting | shares	2,807,500
Stock Issued During Period, Shares, Conversion of Convertible Securities | shares	5,750,000
PIPE Investors [Member] | Sandbridge [Member]
Subsidiary, Sale of Stock [Line Items]
Proceeds from reverse recapitalization and PIPE financing	$ 129,680
Sale of stock, Number of shares issued in transaction | shares	12,968,000
Consideration received	$ 129,680
Sale of stock, price per share | $ / shares	$ 10.00
Old Owlet [Member]
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Conversion Basis				All 30,104,000 outstanding shares of Old Owlet redeemable convertible preferred stock were converted into an equivalent number of shares of Old Owlet common stock on a one-to-one basis.
Preferred Stock, Convertible, Conversion Price | $ / shares	$ 3.1546
Warrants exercised | shares	429,314
Number of common stock exchanged | shares	90,824,573
Convertible preferred stock, conversion ratio	2.053
Sale of stock, price per share | $ / shares	$ 20.53
Old Owlet [Member] | Common Class A [Member]
Subsidiary, Sale of Stock [Line Items]
Preferred stock shares outstanding | shares	30,104,000
Old Owlet [Member] | Common Class B [Member]
Subsidiary, Sale of Stock [Line Items]
Preferred stock shares outstanding | shares	30,104,000
Old Owlet [Member] | Series A Preferred Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Warrants exercised | shares	433,356
Amount of warrant consideration and settled	$ 0
Old Owlet [Member] | Related Party Convertible Promissory [Member]
Subsidiary, Sale of Stock [Line Items]
Principal And Accrued Interest	7,122
Amount of convertible notes redeemed for cash	$ 2