Fair Value Measurements and Disclosures Notes Receivable (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
1.125% Convertible Senior Notes due 2021 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 185.2	$ 175.4
Senior Notes fair value	92.60%	87.70%
5.75% Senior Notes due 2026 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 589.8	$ 532.4
Senior Notes fair value	98.30%	88.70%
6.125% Senior Notes due 2024 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes Payable, Fair Value Disclosure	$ 400.0	$ 370.2
Senior Notes fair value	100.00%	92.50%