Douglas Dynamics, Inc. Annual report pursuant to Section 13 and 15(d)

Changes in Accumulated Other Comprehensive Loss by Component - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net									$ 20,238	$ 16,782	$ 16,943
Tax expense (benefit)									(12,276)	13,451	11,854
Reclassification net of tax	$ (18,162)	$ (9,230)	$ 103,859	$ 10,086	$ (11,560)	$ (12,429)	$ (25,474)	$ 297	86,553	(48,527)	$ (43,321)
Other Postretirement Benefit Liability \| Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses									(310)	(312)
Tax expense (benefit)									81	78
Reclassification net of tax									(229)	(234)
Pension Liability \| Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Actuarial (gains) losses										595
Tax expense (benefit)										(149)
Reclassification net of tax										446
Unrealized Net Loss on Interest Rate Swap \| Interest rate swap \| Amount reclassified from accumulated other comprehensive income
Amounts reclassified from accumulated other comprehensive loss:
Interest expense, net									3,327	499
Tax expense (benefit)									(865)	(125)
Reclassification net of tax									$ 2,462	$ 374