Indebtedness - Summary of Debt Exchange Offer to Exchange All Validly Tendered and Accepted Range Senior Subordinated Notes (Parenthetical) (Detail)	Dec. 31, 2017	Oct. 05, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 16, 2016
5.00% Senior Subordinated Notes Due 2023
Debt Instrument [Line Items]
Interest rate on notes	5.00%		5.00%		5.00%
5.00% Senior Subordinated Notes Due 2022
Debt Instrument [Line Items]
Interest rate on notes	5.00%		5.00%		5.00%
5.75% Senior Subordinated Notes Due 2021
Debt Instrument [Line Items]
Interest rate on notes	5.75%		5.75%		5.75%
5.00% Senior Notes Due 2023
Debt Instrument [Line Items]
Interest rate on notes	5.00%	5.00%	5.00%	5.00%	5.00%
5.00% Senior Notes Due 2022
Debt Instrument [Line Items]
Interest rate on notes	5.00%	5.00%	5.00%	5.00%	5.00%
5.75% Senior Notes Due 2021
Debt Instrument [Line Items]
Interest rate on notes	5.75%	5.75%	5.75%	5.75%	5.75%