Regulatory Capital and Reserve Requirements Regulatory Capital and Reserve Requirements (Tables)

12 Months Ended

Dec. 31, 2019

Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]

Summary of Capital Position

The following is a summary of the capital position of the Corporation and Comerica Bank, its principal banking subsidiary.

(dollar amounts in millions)	Comerica Incorporated (Consolidated)			Comerica Bank
December 31, 2019
CET1 capital (minimum $3.1 billion (Consolidated))	$	6,919		$	7,199
Tier 1 capital (minimum $4.1 billion (Consolidated))	6,919			7,199
Total capital (minimum $5.5 billion (Consolidated))	8,282			8,371
Risk-weighted assets	68,273			68,071
Average assets (fourth quarter)	72,773			72,564
CET1 capital to risk-weighted assets (minimum-4.5%)	10.13		%	10.58		%
Tier 1 capital to risk-weighted assets (minimum-6.0%)	10.13			10.58
Total capital to risk-weighted assets (minimum-8.0%)	12.13			12.30
Tier 1 capital to average assets (minimum-4.0%)	9.51			9.92
Capital conservation buffer (minimum-2.5%)	4.13			4.30
December 31, 2018
CET1 capital (minimum $3.0 billion (Consolidated))	$	7,470		$	7,229
Tier 1 capital (minimum $4.0 billion (Consolidated))	7,470			7,229
Total capital (minimum $5.4 billion (Consolidated))	8,855			8,433
Risk-weighted assets	67,047			66,857
Average assets (fourth quarter)	71,070			70,905
CET1 capital to risk-weighted assets (minimum-4.5%)	11.14		%	10.81		%
Tier 1 capital to risk-weighted assets (minimum-6.0%)	11.14			10.81
Total capital to risk-weighted assets (minimum-8.0%)	13.21			12.61
Tier 1 capital to average assets (minimum-4.0%)	10.51			10.20
Capital conservation buffer (minimum-2.5%)	5.14			4.61