Litigation Contingencies - Litigation Contingencies (Details) - Consumer Financial Protection Bureau v. TCF National Bank $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Loss Contingencies
Restitution to certain current and former customers	$ 25.0
Civil money penalties	5.0
Administrative settlement costs	2.0
OCC
Loss Contingencies
Civil money penalties	3.0
CFPB
Loss Contingencies
Civil money penalties	$ 2.0