Income Per Share - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Line Items]
Loss on call spread modification related to convertible notes	$ 4,952		$ 4,952
3.75% Convertible Senior Notes [Member]
Earnings Per Share [Line Items]
Interest		3.75%
Maturity year of note		2014