Condensed Guarantor and Non-Guarantor Financial Information, Cash Flow Statements (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net cash (used in) provided by operating activities		$ 153.9	$ 112.5
Cash flows from investing activities
Capital expenditures		(40.7)	(53.1)
Purchase of available for sale securities		(56.3)	(111.9)
Purchase of equity securities		(0.7)	(0.9)
Proceeds from disposition of available for sale securities		68.2	208.7
Cash payment for acquisition of Imperial Machine & Tool Co., net of cash received		0.0	(43.3)
Proceeds from disposition of property, plant and equipment		0.2	0.6
Intercompany loans receivable		0.0	0.0
Net cash (used in) provided by investing activities	[1]	(29.3)	0.1
Cash flows from financing activities
Repayment of finance lease		(1.1)	(0.5)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(6.2)	(6.9)
Repurchase of common stock		(40.6)	(31.9)
Cash dividends paid to Parent		0.0	0.0
Cash dividends and dividend equivalents paid		(29.8)	(28.5)
Intercompany loans payable		0.0	0.0
Net cash used in financing activities	[1]	(77.7)	(67.8)
Net increase in cash, cash equivalents, and restricted cash during the period		46.9	44.8
Cash, cash equivalents and restricted cash at beginning of period		139.6	64.3
Cash, cash equivalents and restricted cash at end of period		186.5	109.1
Consolidating Adjustments
Cash flows from operating activities:
Net cash (used in) provided by operating activities		(0.5)	(100.0)
Cash flows from investing activities
Capital expenditures		0.0	0.0
Purchase of available for sale securities		0.0	0.0
Purchase of equity securities		0.0	0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Cash payment for acquisition of Imperial Machine & Tool Co., net of cash received			0.0
Proceeds from disposition of property, plant and equipment		0.0	0.0
Intercompany loans receivable		(83.4)	21.7
Net cash (used in) provided by investing activities		(83.4)	21.7
Cash flows from financing activities
Repayment of finance lease		0.0	0.0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		0.0	0.0
Repurchase of common stock		0.0	0.0
Cash dividends paid to Parent		0.5	100.0
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		83.4	(21.7)
Net cash used in financing activities		83.9	78.3
Net increase in cash, cash equivalents, and restricted cash during the period		0.0	0.0
Cash, cash equivalents and restricted cash at beginning of period		0.0	0.0
Cash, cash equivalents and restricted cash at end of period		0.0	0.0
Parent
Cash flows from operating activities:
Net cash (used in) provided by operating activities		(16.5)	87.5
Cash flows from investing activities
Capital expenditures		0.0	0.0
Purchase of available for sale securities		0.0	0.0
Purchase of equity securities		0.0	0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Cash payment for acquisition of Imperial Machine & Tool Co., net of cash received			0.0
Proceeds from disposition of property, plant and equipment		0.0	0.0
Intercompany loans receivable		93.1	(20.2)
Net cash (used in) provided by investing activities		93.1	(20.2)
Cash flows from financing activities
Repayment of finance lease		0.0	0.0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(6.2)	(6.9)
Repurchase of common stock		(40.6)	(31.9)
Cash dividends paid to Parent		0.0	0.0
Cash dividends and dividend equivalents paid		(29.8)	(28.5)
Intercompany loans payable		0.0	0.0
Net cash used in financing activities		(76.6)	(67.3)
Net increase in cash, cash equivalents, and restricted cash during the period		0.0	0.0
Cash, cash equivalents and restricted cash at beginning of period		0.0	0.0
Cash, cash equivalents and restricted cash at end of period		0.0	0.0
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash (used in) provided by operating activities		163.6	78.5
Cash flows from investing activities
Capital expenditures		(39.4)	(51.9)
Purchase of available for sale securities		(56.3)	(111.9)
Purchase of equity securities		(0.7)	(0.9)
Proceeds from disposition of available for sale securities		68.2	208.7
Cash payment for acquisition of Imperial Machine & Tool Co., net of cash received			0.0
Proceeds from disposition of property, plant and equipment		0.2	0.6
Intercompany loans receivable		(1.3)	(0.4)
Net cash (used in) provided by investing activities		(29.3)	44.2
Cash flows from financing activities
Repayment of finance lease		(1.1)	(0.5)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		0.0	0.0
Repurchase of common stock		0.0	0.0
Cash dividends paid to Parent		0.0	(100.0)
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		(84.7)	21.4
Net cash used in financing activities		(85.8)	(79.1)
Net increase in cash, cash equivalents, and restricted cash during the period		48.5	43.6
Cash, cash equivalents and restricted cash at beginning of period		136.3	61.3
Cash, cash equivalents and restricted cash at end of period		184.8	104.9
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash (used in) provided by operating activities		7.3	46.5
Cash flows from investing activities
Capital expenditures		(1.3)	(1.2)
Purchase of available for sale securities		0.0	0.0
Purchase of equity securities		0.0	0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Cash payment for acquisition of Imperial Machine & Tool Co., net of cash received			(43.3)
Proceeds from disposition of property, plant and equipment		0.0	0.0
Intercompany loans receivable		(8.4)	(1.1)
Net cash (used in) provided by investing activities		(9.7)	(45.6)
Cash flows from financing activities
Repayment of finance lease		0.0	0.0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		0.0	0.0
Repurchase of common stock		0.0	0.0
Cash dividends paid to Parent		(0.5)	0.0
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		1.3	0.3
Net cash used in financing activities		0.8	0.3
Net increase in cash, cash equivalents, and restricted cash during the period		(1.6)	1.2
Cash, cash equivalents and restricted cash at beginning of period		3.3	3.0
Cash, cash equivalents and restricted cash at end of period		$ 1.7	$ 4.2

[1] See Note 12 for supplemental cash flow information.