Condensed Guarantor and Non-Guarantor Financial Statements, Cash Flow Statements (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net cash provided by operating activities				$ 72.1	$ 48.3
Cash flows from investing activities
Capital expenditures		$ (16.4)	$ (11.6)	(42.3)	(22.9)
Purchase of available for sale securities				(72.4)	(0.5)
Proceeds from disposition of available for sale securities				30.0	84.0
Change in Intercompany Loans Receivable				0.0
Net cash (used in) provided by investing activities	[1]			(84.7)	60.6
Cash flows from financing activities
Repayment of Convertible Notes				0.0	(175.0)
Proceeds from cash-settled call options related to repayment of Convertible Notes				0.0	94.9
Payment for conversion premium related to repayment of Convertible Notes				0.0	(94.9)
Repayment of principal and redemption premium of 8.25% Senior Notes				(206.0)	0.0
Issuance of 5.875% Senior Notes				375.0	0.0
Cash paid for debt issuance costs				(6.9)	0.0
Proceeds from stock option exercises				1.0	0.0
Repayment of capital lease				(0.1)	0.0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	[2]			0.0	1.1
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares				(2.8)	(3.0)
Repurchase of common stock				(8.5)	(41.4)
Cash dividends paid to stockholders				(16.3)	(14.0)
Intercompany loan					0.0
Cash dividends paid to Parent				0.0
Intercompany loans payable1				0.0
Net cash provided by (used in) financing activities	[1]			135.4	(232.3)
Net increase in cash and cash equivalents during the period				122.8	(123.4)
Cash and cash equivalents at beginning of period				72.5	177.7
Cash and cash equivalents at end of period		195.3	54.3	195.3	54.3
Consolidating Adjustments
Cash flows from operating activities:
Net cash provided by operating activities				(200.0)	0.0
Cash flows from investing activities
Capital expenditures				0.0	0.0
Purchase of available for sale securities				0.0	0.0
Proceeds from disposition of available for sale securities				0.0	0.0
Change in Intercompany Loans Receivable				115.9
Net cash (used in) provided by investing activities				115.9	0.0
Cash flows from financing activities
Repayment of Convertible Notes					0.0
Proceeds from cash-settled call options related to repayment of Convertible Notes					0.0
Payment for conversion premium related to repayment of Convertible Notes					0.0
Repayment of principal and redemption premium of 8.25% Senior Notes				0.0
Issuance of 5.875% Senior Notes				0.0
Cash paid for debt issuance costs				0.0
Proceeds from stock option exercises				0.0
Repayment of capital lease				0.0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest					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 stockholders				0.0	0.0
Intercompany loan					0.0
Cash dividends paid to Parent				200.0
Intercompany loans payable1				(115.9)
Net cash provided by (used in) financing activities				84.1	0.0
Net increase in cash and cash equivalents during the period				0.0	0.0
Cash and cash equivalents at beginning of period				0.0	0.0
Cash and cash equivalents at end of period		0.0	0.0	0.0	0.0
Parent
Cash flows from operating activities:
Net cash provided by operating activities				190.7	233.4
Cash flows from investing activities
Capital expenditures				0.0	0.0
Purchase of available for sale securities				0.0	0.0
Proceeds from disposition of available for sale securities				0.0	0.0
Change in Intercompany Loans Receivable				(219.7)
Net cash (used in) provided by investing activities				(219.7)	0.0
Cash flows from financing activities
Repayment of Convertible Notes					(175.0)
Proceeds from cash-settled call options related to repayment of Convertible Notes					94.9
Payment for conversion premium related to repayment of Convertible Notes					(94.9)
Repayment of principal and redemption premium of 8.25% Senior Notes				(206.0)
Issuance of 5.875% Senior Notes				375.0
Cash paid for debt issuance costs				(6.9)
Proceeds from stock option exercises				1.0
Repayment of capital lease				0.0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest					0.0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares				(2.8)	(3.0)
Repurchase of common stock				(8.5)	(41.4)
Cash dividends paid to stockholders				(16.3)	(14.0)
Intercompany loan					0.0
Cash dividends paid to Parent				0.0
Intercompany loans payable1				(106.5)
Net cash provided by (used in) financing activities				29.0	(233.4)
Net increase in cash and cash equivalents during the period				0.0	0.0
Cash and cash equivalents at beginning of period				0.0	0.0
Cash and cash equivalents at end of period		0.0	0.0	0.0	0.0
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash provided by operating activities				76.1	(190.1)
Cash flows from investing activities
Capital expenditures				(40.8)	(14.3)
Purchase of available for sale securities				(72.4)	(0.5)
Proceeds from disposition of available for sale securities				30.0	84.0
Change in Intercompany Loans Receivable				106.2
Net cash (used in) provided by investing activities				23.0	69.2
Cash flows from financing activities
Repayment of Convertible Notes					0.0
Proceeds from cash-settled call options related to repayment of Convertible Notes					0.0
Payment for conversion premium related to repayment of Convertible Notes					0.0
Repayment of principal and redemption premium of 8.25% Senior Notes				0.0
Issuance of 5.875% Senior Notes				0.0
Cash paid for debt issuance costs				0.0
Proceeds from stock option exercises				0.0
Repayment of capital lease				0.0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest					1.1
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 stockholders				0.0	0.0
Intercompany loan					(5.7)
Cash dividends paid to Parent				(200.0)
Intercompany loans payable1				222.1
Net cash provided by (used in) financing activities				22.1	(4.6)
Net increase in cash and cash equivalents during the period				121.2	(125.5)
Cash and cash equivalents at beginning of period				72.2	175.3
Cash and cash equivalents at end of period		193.4	49.8	193.4	49.8
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash provided by operating activities				5.3	5.0
Cash flows from investing activities
Capital expenditures				(1.5)	(8.6)
Purchase of available for sale securities				0.0	0.0
Proceeds from disposition of available for sale securities				0.0	0.0
Change in Intercompany Loans Receivable				(2.4)
Net cash (used in) provided by investing activities				(3.9)	(8.6)
Cash flows from financing activities
Repayment of Convertible Notes					0.0
Proceeds from cash-settled call options related to repayment of Convertible Notes					0.0
Payment for conversion premium related to repayment of Convertible Notes					0.0
Repayment of principal and redemption premium of 8.25% Senior Notes				0.0
Issuance of 5.875% Senior Notes				0.0
Cash paid for debt issuance costs				0.0
Proceeds from stock option exercises				0.0
Repayment of capital lease				(0.1)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest					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 stockholders				0.0	0.0
Intercompany loan					5.7
Cash dividends paid to Parent				0.0
Intercompany loans payable1				0.3
Net cash provided by (used in) financing activities				0.2	5.7
Net increase in cash and cash equivalents during the period				1.6	2.1
Cash and cash equivalents at beginning of period				0.3	2.4
Cash and cash equivalents at end of period		$ 1.9	$ 4.5	$ 1.9	$ 4.5

[1] See Note 12 for the supplemental disclosure on non-cash transactions.

[2] See Note 4 and Note 6 for discussion of our adoption of ASU 2016-09 (as defined in Note 1).