Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Operating activities
Net (loss) income	$ (88.3)	$ (45.6)	$ 15.0	$ 10.9	$ (173.7)	$ 42.2
Adjustments to reconcile net (loss) income to net cash provided by operations:
Impairments					231.1
Depreciation and amortization					23.0	21.8
Non-cash stock-based compensation					(2.2)	3.1
Provisions for credit losses on accounts receivable					6.0	0.5	$ 2.1
Deferred income taxes					(64.3)	1.8
Other					2.3	0.1
Changes in operating assets and liabilities
Notes and accounts receivable					52.7	0.2
Prepaid and other current assets					10.0	1.9
Accounts payable					(14.1)	(7.6)
Accrued liabilities and other					(42.9)	(9.2)
Net cash provided by operating activities					27.9	54.8
Investing activities
Purchases of leasehold improvements and equipment					(5.8)	(6.4)
Cost of contracts purchased					(2.3)	(2.1)
Proceeds from sale of other investments and equipment					0.8	0.3
Noncontrolling interest buyout					(1.7)
Net cash used in investing activities					(9.0)	(8.2)
Financing activities
Payments on credit facility revolver					(401.5)	(360.3)
Proceeds from credit facility revolver					404.2	347.8
Payments on credit facility term loan					(8.4)	(8.4)
Payments on other long-term borrowings					(5.0)	(1.6)
Distributions to noncontrolling interest					(1.1)	(2.4)
Repurchases of common stock					(15.3)	(32.0)
Net cash used in financing activities					(27.1)	(56.9)
Effect of exchange rate changes on cash and cash equivalents					(0.3)
Decrease in cash and cash equivalents					(8.5)	(10.3)
Cash and cash equivalents at beginning of year		$ 24.1		$ 39.9	24.1	39.9	39.9
Cash and cash equivalents at end of period	$ 15.6		$ 29.6		15.6	29.6	$ 24.1
Cash paid during the period for
Interest					13.7	13.8
Income taxes					$ 0.8	$ 11.6