Fair Value Measurements - Carrying Amounts and Fair Values of Financial Instruments (Parenthetical) (Detail)	Dec. 31, 2013		Dec. 31, 2012
7.25% Senior Subordinated notes due 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	7.25%	[1]	7.25%	[1]
8.00% Senior Subordinated notes due 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	8.00%	[1]	8.00%	[1]
6.75% Senior Subordinated notes due 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	6.75%	[1]	6.75%	[1]
5.75% Senior Subordinated Notes due 2021
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	5.75%	[1]	5.75%	[1]
5.00% Senior Subordinated notes due 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	5.00%	[1]	5.00%	[1]
5.00% Senior Subordinated notes due 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest rate on senior subordinated notes	5.00%	[1]	5.00%	[1]

[1] The book value of our bank debt approximates fair value because of its floating rate structure. The fair value of our senior subordinated notes is based on end of period market quotes, which are Level 2 inputs.