Carrying Value of Senior Notes (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total debt	$ 752,641	$ 755,383
Less current portion of term credit facility	59,141	47,313
Total long-term debt	693,500	708,070
Term credit facility
Debt Instrument [Line Items]
Total debt	437,641	455,383
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	15,000
6.375% Senior Notes, due August 2020
Debt Instrument [Line Items]
Total debt	$ 300,000	$ 300,000