Spirit of Texas Bancshares, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Cover
- Document and Entity Information
Financial Statements
Notes to Financial Statements
Accounting Policies
- Summary of Significant Accounting Policies (Policies)
Notes Tables
Notes Details

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.22.0.1

Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Mar. 26, 2020	Dec. 31, 2021 USD ($) Segment $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2021 USD ($)
Subsidiary Sale Of Stock [Line Items]
Insurance Coverage		$ 250,000
Regulatory reserve requirement percentage	0.00%
Marketable equity securities with fair value		$ 23,700,000
Number of reporting units \| Segment		1
Impairment charges		$ 0	$ 0	$ 0
Repurchase of common stock shares \| shares		58,506
Repurchase of common stock average price per share \| $ / shares		$ 18.74
Number of reportable operating segment \| Segment		1
Right of use asset		$ 4,539,000
Lease liability		$ 4,720,000
Accounting Standards Update 2016-02
Subsidiary Sale Of Stock [Line Items]
Right of use asset					$ 6,400,000
Lease liability					$ 6,600,000
Minimum
Subsidiary Sale Of Stock [Line Items]
Loan guarantee, percentage		75.00%
Minimum \| Bank premises
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		30 years
Minimum \| Computer Equipment
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		3 years
Minimum \| Furniture And Equipment
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		5 years
Maximum
Subsidiary Sale Of Stock [Line Items]
Loan guarantee, percentage		85.00%
Maximum \| Core Deposit
Subsidiary Sale Of Stock [Line Items]
Estimated useful life		12 years
Maximum \| Bank premises
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		40 years
Maximum \| Computer Equipment
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		5 years
Maximum \| Furniture And Equipment
Subsidiary Sale Of Stock [Line Items]
Property, Plant and Equipment Useful Life		10 years
Federal Reserve Bank
Subsidiary Sale Of Stock [Line Items]
Cash on hand		$ 210,300,000	$ 224,500,000

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