Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income attributable to TCF Financial Corporation	$ 51,899	$ 70,494
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available-for-sale investment securities and interest-only strips	115,847	37,368
Net unrealized gains (losses) on net investment hedges	10,481	(2,308)
Foreign currency translation adjustment	(14,426)	3,567
Recognized postretirement prior service cost	(9)	(8)
Total other comprehensive income (loss), net of tax	111,893	38,619
Comprehensive income	$ 163,792	$ 109,113