Net Income (Loss) Per Share Attributable to Class A Common Stock (Details) $ / shares in Units, $ in Thousands		3 Months Ended		4 Months Ended	9 Months Ended
	May 21, 2026	Sep. 30, 2026 USD ($) $ / shares shares	Sep. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) $ / shares shares	Sep. 30, 2026 USD ($) $ / shares shares	Sep. 30, 2025 USD ($)
(in thousands, except number of shares and per share amounts)
Net income attributable to Lincoln International Inc. | $		$ 9,935	$ 50,640	$ 10,390	$ 10,390	$ 109,067
Net income impact due to:
Exchange of LILP common units to Class A common stock | $		0		0
Net income (loss) attributable to Lincoln International, Inc. - Diluted | $		$ 9,935		$ 10,390
Denominator:
Common unit to common stock conversion ratio	1
Class A
Denominator:
Weighted average Class A shares issued and outstanding (in shares)		35,693,768			35,428,354
IPO Liquidity shares (in shares)		654,619		898,880
Weighted average shares of Class A common stock - Basic (in shares)		36,348,387		36,327,234	36,327,234
Exchangeable LILP common units (in shares)				0
Weighted average shares of Class A common stock – Diluted (in shares)		39,677,992		39,569,600	39,569,600
Earnings per share of Class A common stock - Basic (in USD per share) | $ / shares		$ 0.27		$ 0.29	$ 0.29
Earnings per share of Class A common stock - Diluted (in USD per share) | $ / shares		$ 0.25		$ 0.26	$ 0.26
IPO Equity Awards (RSUs)
Net income impact due to:
IPO Equity Awards / Options | $		$ 0		$ 0
Denominator:
Vesting period	4 years
IPO Equity Awards (RSUs) | Class A
Denominator:
IPO Equity Awards (RSUs)/ LILP Options (in shares)		712,817		647,127
IPO Equity Awards (RSUs) | Minimum
Denominator:
Vesting period				3 years
IPO Equity Awards (RSUs) | Maximum
Denominator:
Vesting period				4 years
Option
Net income impact due to:
IPO Equity Awards / Options | $		$ 0		$ 0
Option | Class A
Denominator:
IPO Equity Awards (RSUs)/ LILP Options (in shares)		2,616,788		2,595,239