Nature of Operations and Principles of Consolidation - Balance Sheet Impact (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable, net of allowances	$ 194.8	$ 196.4	$ 196.4
Inventories, net	233.1		173.7
Unbilled contract revenue	54.5		36.5
Prepaid expenses	14.0		14.4
Other current assets	47.2		23.7
Liabilities
Accounts payable	125.5		105.4
Customer advances and billings in excess of contract revenue	130.0	$ 101.8	109.6
Other current liabilities	44.7		39.9
Long-term deferred tax liabilities	76.4		62.1
Equity
Retained earnings	453.9		364.3
Balances without adoption of ASC 606
Assets
Accounts receivable, net of allowances	194.7
Inventories, net	254.1		163.2
Unbilled contract revenue	46.5		43.0
Prepaid expenses			12.8
Other current assets	47.3
Liabilities
Accounts payable			105.6
Customer advances and billings in excess of contract revenue	149.6		101.8
Other current liabilities	43.6		40.0
Long-term deferred tax liabilities	75.1		62.4
Equity
Retained earnings	449.7		365.9
Effect of adoption Higher (Lower) | ASU 2014-09
Assets
Accounts receivable, net of allowances	0.1
Inventories, net	(21.0)		(10.5)
Unbilled contract revenue	8.0		6.5
Prepaid expenses			(1.6)
Other current assets	(0.1)
Liabilities
Accounts payable			0.2
Customer advances and billings in excess of contract revenue	(19.6)		(7.8)
Other current liabilities	1.1		0.1
Long-term deferred tax liabilities	1.3		0.3
Equity
Retained earnings	$ 4.2		$ 1.6