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Fair Value Measurement and Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying Values of Financial Instruments (Detail) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Interest rate swap agreements    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Carry value, interest rate swap $ 545 $ 1,163
Fair value, interest rate swap 545 1,163
4.375% Senior Notes    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Carry value, senior notes 248,631 248,567
Fair value, senior notes $ 254,750 262,033
Stated interest rate (as a percent) 4.375%  
3.45% Senior Notes    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Carry value, senior notes $ 747,721 747,655
Fair value, senior notes $ 720,638 $ 741,113
Stated interest rate (as a percent) 3.45%