Stockholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 975,983	$ 1,635,509	$ 1,548,504
Net transfers to/from Dover		(742,054)	(29,543)
Other comprehensive income (loss)	(1,131)	(12,754)	7,241
Ending Balance	1,036,214	975,983	1,635,509
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(36,146)	(21,936)
Reclassification adjustment for cumulative effect of change in accounting principle				$ 0
Net transfers to/from Dover		0
Other comprehensive income (loss) before reclassifications, net of tax	936	(14,210)
Reclassification adjustment for net losses included in net income, net of tax	0	0
Other comprehensive income (loss)	936	(14,210)
Ending Balance	(35,210)	(36,146)	(21,936)
Defined Pension and Other Post-Retirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(6,760)	(4,480)
Reclassification adjustment for cumulative effect of change in accounting principle				(1,315)
Net transfers to/from Dover		(2,421)
Other comprehensive income (loss) before reclassifications, net of tax	(2,711)	856
Reclassification adjustment for net losses included in net income, net of tax	644	600
Other comprehensive income (loss)	(2,067)	1,456
Ending Balance	(8,827)	(6,760)	(4,480)
Accum. Other Comp. Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(42,906)	(26,416)	(33,657)
Reclassification adjustment for cumulative effect of change in accounting principle				$ (1,315)
Net transfers to/from Dover		(2,421)
Other comprehensive income (loss) before reclassifications, net of tax	(1,775)	(13,354)
Reclassification adjustment for net losses included in net income, net of tax	644	600
Other comprehensive income (loss)	(1,131)	(12,754)	7,241
Ending Balance	$ (44,037)	$ (42,906)	$ (26,416)