Fair Value Measurements - Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
2006 Convertible Senior Subordinated Notes [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input [Line Items]
Carrying Value	$ 750	$ 750
Fair Value	750	750
2010 Convertible Senior Subordinated Notes [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input [Line Items]
Carrying Value	126,006	124,506
Fair Value	$ 171,263	$ 173,779