Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 04, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Entity Registrant Name	CAPSTAR FINANCIAL HOLDINGS, INC.
Entity Central Index Key	0001676479
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		21,947,023
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-37886
Entity Tax Identification Number	81-1527911
Entity Address, Address Line One	1201 Demonbreun Street
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Nashville
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	37203
City Area Code	615
Local Phone Number	732-6400
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	TN
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $1.00 par value per share
Trading Symbol	CSTR
Security Exchange Name	NASDAQ