CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Consolidated revenue	$ 525.2	$ 578.6	$ 1,555.2	$ 1,789.9
Consolidated expenses:
Compensation and related expenses	211.8	273.8	663.0	797.0
Selling, general and administrative	91.1	93.2	273.4	275.7
Intangible amortization and impairments	12.5	14.4	37.5	39.4
Interest expense	31.1	28.3	92.4	84.7
Depreciation and other amortization	3.0	3.8	10.0	11.9
Other expenses (net)	7.9	11.9	36.2	12.3
Total consolidated expenses	357.4	425.4	1,112.5	1,221.0
Equity method income (net)	39.8	44.8	154.3	123.9
Affiliate Transaction gain	133.1	0.0	133.1	0.0
Investment and other income (expense)	23.0	3.1	87.2	(5.3)
Income before income taxes	363.7	201.1	817.3	687.5
Income tax expense	77.7	36.8	155.4	130.5
Net income	286.0	164.3	661.9	557.0
Net income (non-controlling interests)	(69.0)	(51.7)	(185.1)	(189.0)
Net income (controlling interest)	$ 217.0	$ 112.6	$ 476.8	$ 368.0
Average shares outstanding (basic) (in shares)	34.9	38.2	35.6	38.8
Average shares outstanding (diluted) (in shares)	43.4	43.5	42.9	47.8
Earnings per share (basic) (in dollars per share)	$ 6.22	$ 2.95	$ 13.41	$ 9.48
Earnings per share (diluted) (in dollars per share)	$ 5.48	$ 2.80	$ 12.28	$ 8.83

Amortization and Impairments of Intangible Assets

No definition available.

Name:	amg_AmortizationandImpairmentsofIntangibleAssets
Namespace Prefix:	amg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate expense charged against earnings to allocate the cost of tangible assets to periods in which the assets are used and held and to allocate the cost of issuing debt to periods in which the debt is outstanding. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.

+ References

No definition available.