Guarantor and Non-Guarantor Financial Statements, Cash Flow Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net cash (used in) provided by operating activities	$ 7.4	$ 27.1
Cash flows from investing activities:
Capital expenditures	(11.3)	(15.4)
Proceeds from disposition of available for sale securities	84.0	25.0
Net cash provided by (used in) investing activities	72.7	9.6
Cash flows from financing activities:
Repayments of Capital Lease Obligations	0.1	0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	1.0	0.7
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	(2.5)	(2.2)
Repurchase of common stock	(28.2)	(12.7)
Cash dividend paid to stockholders	(7.1)	(6.4)
Intercompany loan	0	0
Net cash used in financing activities	(36.9)	(20.6)
Net increase (decrease) in cash and cash equivalents during the period	43.2	16.1
Cash and cash equivalents at beginning of period	177.7	169.5
Cash and cash equivalents at end of period	220.9	185.6
Parent
Cash flows from operating activities:
Net cash (used in) provided by operating activities	37.8	(11.0)
Cash flows from investing activities:
Capital expenditures	0	0
Proceeds from disposition of available for sale securities	0	0
Net cash provided by (used in) investing activities	0	0
Cash flows from financing activities:
Repayments of Capital Lease Obligations	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	(2.5)	(2.2)
Repurchase of common stock	(28.2)	(12.7)
Cash dividend paid to stockholders	(7.1)	(6.4)
Intercompany loan	0	32.3
Net cash used in financing activities	(37.8)	11.0
Net increase (decrease) in cash and cash equivalents during the period	0	0
Cash and cash equivalents at beginning of period	0	5.0
Cash and cash equivalents at end of period	0	5.0
Guarantor Subsidiaries
Cash flows from operating activities:
Net cash (used in) provided by operating activities	(32.7)	35.8
Cash flows from investing activities:
Capital expenditures	(6.7)	(15.4)
Proceeds from disposition of available for sale securities	84.0	25.0
Net cash provided by (used in) investing activities	77.3	9.6
Cash flows from financing activities:
Repayments of Capital Lease Obligations	0.1
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	1.0	0.7
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	0	0
Repurchase of common stock	0	0
Cash dividend paid to stockholders	0	0
Intercompany loan	(1.9)	(29.5)
Net cash used in financing activities	(1.0)	(28.8)
Net increase (decrease) in cash and cash equivalents during the period	43.6	16.6
Cash and cash equivalents at beginning of period	175.3	157.7
Cash and cash equivalents at end of period	218.9	174.3
Non-Guarantor Subsidiaries
Cash flows from operating activities:
Net cash (used in) provided by operating activities	2.3	2.3
Cash flows from investing activities:
Capital expenditures	(4.6)	0
Proceeds from disposition of available for sale securities	0	0
Net cash provided by (used in) investing activities	(4.6)	0
Cash flows from financing activities:
Repayments of Capital Lease Obligations	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
Repurchase of common stock	0	0
Cash dividend paid to stockholders	0	0
Intercompany loan	1.9	(2.8)
Net cash used in financing activities	1.9	(2.8)
Net increase (decrease) in cash and cash equivalents during the period	(0.4)	(0.5)
Cash and cash equivalents at beginning of period	2.4	6.8
Cash and cash equivalents at end of period	2.0	6.3
Consolidating Adjustments
Cash flows from operating activities:
Net cash (used in) provided by operating activities	0	0
Cash flows from investing activities:
Capital expenditures	0	0
Proceeds from disposition of available for sale securities	0	0
Net cash provided by (used in) investing activities	0	0
Cash flows from financing activities:
Repayments of Capital Lease Obligations	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
Repurchase of common stock	0	0
Cash dividend paid to stockholders	0	0
Intercompany loan	0	0
Net cash used in financing activities	0	0
Net increase (decrease) in cash and cash equivalents during the period	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0