Condensed Guarantor and Non-Guarantor Financial Information, Cash Flow Statements (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net cash (used in) provided by operating activities		$ 22.8	$ 26.1
Cash flows from investing activities
Capital expenditures		(13.6)	(19.7)
Purchase of available for sale securities		(18.1)	0.0
Proceeds from disposition of available for sale securities		32.7	100.3
Intercompany loans receivable		0.0	0.0
Net cash provided by investing activities	[1]	1.0	80.6
Cash flows from financing activities
Repayment of finance lease		(0.3)	(0.2)
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares		(5.0)	(6.9)
Repurchase of common stock		(18.5)	(5.7)
Cash dividends paid to Parent			0.0
Cash dividends and dividend equivalents paid		(10.2)	(10.0)
Intercompany loans payable		0.0	0.0
Net cash used in financing activities	[1]	(34.0)	(22.8)
Net increase in cash, cash equivalents, and restricted cash during the period		(10.2)	83.9
Cash, cash equivalents and restricted cash at beginning of period		139.6	64.3
Cash, cash equivalents and restricted cash at end of period		129.4	148.2
Consolidating Adjustments
Cash flows from operating activities:
Net cash (used in) provided by operating activities		0.0	(100.0)
Cash flows from investing activities
Capital expenditures		0.0	0.0
Purchase of available for sale securities		0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Intercompany loans receivable		(39.3)	77.0
Net cash provided by investing activities		(39.3)	77.0
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			100.0
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		39.3	(77.0)
Net cash used in financing activities		39.3	23.0
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		(3.3)	99.7
Cash flows from investing activities
Capital expenditures		0.0	0.0
Purchase of available for sale securities		0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Intercompany loans receivable		37.0	(77.1)
Net cash provided by investing activities		37.0	(77.1)
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		(5.0)	(6.9)
Repurchase of common stock		(18.5)	(5.7)
Cash dividends paid to Parent			0.0
Cash dividends and dividend equivalents paid		(10.2)	(10.0)
Intercompany loans payable		0.0	0.0
Net cash used in financing activities		(33.7)	(22.6)
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		27.2	25.6
Cash flows from investing activities
Capital expenditures		(13.3)	(19.4)
Purchase of available for sale securities		(18.1)
Proceeds from disposition of available for sale securities		32.7	100.3
Intercompany loans receivable		(0.2)	0.0
Net cash provided by investing activities		1.1	80.9
Cash flows from financing activities
Repayment of finance lease		(0.3)	(0.2)
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			(100.0)
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		(39.3)	77.0
Net cash used in financing activities		(39.6)	(23.2)
Net increase in cash, cash equivalents, and restricted cash during the period		(11.3)	83.3
Cash, cash equivalents and restricted cash at beginning of period		136.3	61.3
Cash, cash equivalents and restricted cash at end of period		125.0	144.6
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash (used in) provided by operating activities		(1.1)	0.8
Cash flows from investing activities
Capital expenditures		(0.3)	(0.3)
Purchase of available for sale securities		0.0
Proceeds from disposition of available for sale securities		0.0	0.0
Intercompany loans receivable		2.5	0.1
Net cash provided by investing activities		2.2	(0.2)
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		0.0	0.0
Repurchase of common stock		0.0	0.0
Cash dividends paid to Parent			0.0
Cash dividends and dividend equivalents paid		0.0	0.0
Intercompany loans payable		0.0	0.0
Net cash used in financing activities		0.0	0.0
Net increase in cash, cash equivalents, and restricted cash during the period		1.1	0.6
Cash, cash equivalents and restricted cash at beginning of period		3.3	3.0
Cash, cash equivalents and restricted cash at end of period		$ 4.4	$ 3.6

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