Debt - Summary of Debt (Parenthetical) (Detail)	Mar. 31, 2017	Mar. 24, 2017	Mar. 04, 2017	Dec. 31, 2016
6.375% Senior Unsecured Notes Due 2022 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	6.375%			6.375%
5.750% Senior Unsecured Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	5.75%		5.75%	5.75%
4.000% Senior Unsecured Notes due 2022 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	4.00%			4.00%
5.500% Senior Unsecured Notes Due 2024 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	5.50%			5.50%
6.375% Senior Unsecured Notes due 2024 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	6.375%			6.375%
3.325% Senior Unsecured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	3.325%	3.325%		3.325%
5.250% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Senior unsecured notes, interest rate	5.25%			5.25%