Fair Value Measurements - Fair Values and Related Carrying Values of Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value	$ 260,470	$ 273,931
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	$ 269,705	$ 285,441