Debt - Schedule of the Company's Debt (Detail) - USD ($)		Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Borrowings under the credit facilities		$ 216,000,000	$ 185,000,000	$ 0
Other	[1]	10,800,000	8,500,000
Unamortized debt issuance costs		(11,600,000)	(16,500,000)
Total debt		2,109,700,000	2,387,400,000
Less: current portion		(10,800,000)	(8,200,000)
Long-term debt		2,098,900,000	2,379,200,000
11.25% Senior Notes Due February 1, 2019
Debt Instrument [Line Items]
Senior notes	[2]	172,200,000	172,200,000
7.625% Senior Notes Due June 15, 2020
Debt Instrument [Line Items]
Senior notes		238,400,000	350,000,000
7.875% Senior Notes Due March 15, 2021
Debt Instrument [Line Items]
Senior notes		447,200,000	448,800,000
8.875% Debentures Due April 15, 2021
Debt Instrument [Line Items]
Debentures		80,900,000	80,900,000
7.00% Senior Notes Due February 15, 2022
Debt Instrument [Line Items]
Senior notes		140,000,000	140,000,000
6.50% Senior Notes Due November 15, 2023
Debt Instrument [Line Items]
Senior notes		290,600,000	350,000,000
6.00% Senior Notes Due April 1, 2024
Debt Instrument [Line Items]
Senior notes		298,300,000	400,000,000
6.625% Debentures Due April 15, 2029
Debt Instrument [Line Items]
Debentures		157,900,000	199,500,000
8.820% Debentures Due April 15, 2031
Debt Instrument [Line Items]
Debentures		$ 69,000,000	$ 69,000,000

[1] Includes miscellaneous debt obligations and capital leases.

[2] As of December 31, 2017 and 2016, the interest rate on the 11.25% senior notes due February 1, 2019 was 13.25%, the maximum amount of these rates as a result of credit ratings downgrades.