Parent Company Financial Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Share-based compensation expense			$ 17,762	$ 14,040
Depreciation and amortization			207,954	153,018
Provision (benefit) for deferred income taxes			(27,732)	33,409
Net change in other assets			(188,081)	21,984
Net change in other liabilities			16,229	(1,849)
Other, net			(34,793)	(29,668)
Net cash provided by (used in) operating activities			155,922	410,480
Cash flows from investing activities
Purchases of premises and equipment and lease equipment			(108,404)	(903,394)
Other, net			(6,743)	15,151
Net cash provided by (used in) investing activities			1,831,104	(206,749)
Cash flows from financing activities
Redemption of Series B preferred stock			0	(100,000)
Repurchases of common stock			(58,804)	(149,912)
Common shares sold to TCF employee benefit plans			0	715
Dividends paid on preferred stock			(7,481)	(9,094)
Dividends paid on common stock			(102,368)	(74,916)
Payments related to tax-withholding upon conversion of share-based awards			(5,813)	(6,563)
Exercise of stock options			0	(997)
Net cash provided by (used in) financing activities			(1,251,069)	(255,545)
Net change in cash and due from banks			735,957	(51,814)
Cash and cash equivalents at beginning of period			587,057	621,782
Cash and cash equivalents at end of period	$ 1,323,014	$ 569,968	1,323,014	569,968
TCF
Condensed Cash Flow Statements, Captions [Line Items]
Net income	22,148	86,199	183,069	218,706
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in undistributed (earnings) loss of TCF Bank	(69,483)	(54,892)	(90,527)	108,713
Share-based compensation expense			17,762	14,041
Depreciation and amortization			99	26
Provision (benefit) for deferred income taxes			14	0
Net (losses) gains on sales of assets			(8)	(387)
Net change in other assets			(887)	975
Net change in other liabilities			(13,104)	(374)
Other, net			(2,756)	(100)
Net cash provided by (used in) operating activities			93,662	341,600
Cash flows from investing activities
Purchases of premises and equipment and lease equipment			(51)	(3)
Proceeds from sales of premises and equipment			28	17
Net cash acquired in business combination			155,154	0
Other, net			0	665
Net cash provided by (used in) investing activities			155,131	679
Cash flows from financing activities
Redemption of Series B preferred stock			0	(100,000)
Repurchases of common stock			(58,805)	(149,912)
Common shares sold to TCF employee benefit plans			0	715
Dividends paid on preferred stock			(7,482)	(9,094)
Dividends paid on common stock			(102,368)	(74,916)
Payments related to tax-withholding upon conversion of share-based awards			(5,813)	(6,563)
Exercise of stock options			0	(998)
Net cash provided by (used in) financing activities			(174,468)	(340,768)
Net change in cash and due from banks			74,325	1,511
Cash and cash equivalents at beginning of period			91,132	80,471
Cash and cash equivalents at end of period	$ 165,457	$ 81,982	$ 165,457	$ 81,982