Regulatory Capital Requirements - Regulatory Capital Requirements (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations
Number of prior calendar years considered for payment of dividends in excess of net retained profit		2 years
TCF
Regulatory Capital:
Common Equity Tier 1 Capital		$ 2,224,183		$ 2,242,410
Tier 1 capital		2,408,393		2,522,178
Total capital		$ 2,750,581		$ 2,889,323
Common equity Tier 1 capital ratio
Actual, Ratio		10.82%		10.79%
Tier 1 risk-based capital ratio
Actual, Ratio		11.72%		12.14%
Total risk-based capital ratio
Actual, Ratio		13.38%		13.90%
Tier 1 leverage ratio
Actual, Ratio		10.44%		11.12%
TCF Bank
Compliance with Regulatory Capital Requirements under Banking Regulations
Net profits for the current year combined with retained net profits for preceding two calendar years		$ 235,400
Capital conservation buffer excluded from minimum capital requirement		1.875%		1.25%
Regulatory Capital:
Common Equity Tier 1 Capital		$ 2,282,013		$ 2,409,027
Tier 1 capital		2,300,472		2,426,854
Total capital		$ 2,675,347		$ 2,837,374
Common equity Tier 1 capital ratio
Actual, Ratio		11.10%		11.59%
Well-Capitalized Capital Requirement, Ratio		6.50%
Minimum Capital Requirement, Ratio	[1]	4.50%
Tier 1 risk-based capital ratio
Actual, Ratio		11.19%		11.68%
Well-Capitalized Capital Requirement, Ratio		8.00%
Minimum Capital Requirement, Ratio	[1]	6.00%
Total risk-based capital ratio
Actual, Ratio		13.01%		13.65%
Well-Capitalized Capital Requirement, Ratio		10.00%
Minimum Capital Requirement, Ratio	[1]	8.00%
Tier 1 leverage ratio
Actual, Ratio		9.97%		10.70%
Well-Capitalized Capital Requirement, Ratio		5.00%
Minimum Capital Requirement, Ratio	[1]	4.00%
Scenario, Forecast | TCF Bank
Compliance with Regulatory Capital Requirements under Banking Regulations
Capital conservation buffer excluded from minimum capital requirement			2.50%
Common equity Tier 1 capital ratio
Minimum Capital Requirement, Ratio			7.00%
Tier 1 risk-based capital ratio
Minimum Capital Requirement, Ratio			8.50%
Total risk-based capital ratio
Minimum Capital Requirement, Ratio			10.50%
Maximum
Compliance with Regulatory Capital Requirements under Banking Regulations
Percentage of net retained profits for the current year combined with retained net profits for the preceding two calendar years that can be declared as dividend		100.00%

[1] (1) Excludes capital conservation buffer of 1.875% and 1.25% at December 31, 2018 and 2017, respectively.