Borrowings (Schedule of Borrowings) (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total borrowings	$ 955,869	$ 1,020,873
Less current portion	323	1,046
Less deferred debt issuance costs	4,133	4,399
Less unaccreted debt discount	1,130	1,193
Total long-term borrowings	950,283	1,014,235
Revolving Facility
Debt Instrument [Line Items]
Revolving Facility	105,342	169,579
Senior Notes | 4.5% Senior Notes, due December 2020
Debt Instrument [Line Items]
Total borrowings	300,000	300,000
Senior Notes | 4.2% Senior Notes, due December 2021
Debt Instrument [Line Items]
Total borrowings	350,000	350,000
Senior Notes | 3.2% Senior Notes, due June 2023
Debt Instrument [Line Items]
Total borrowings	100,000	100,000
Senior Notes | 3.37% Senior Notes, due June 2025
Debt Instrument [Line Items]
Total borrowings	100,000	100,000
Other borrowings
Debt Instrument [Line Items]
Other borrowings	$ 527	$ 1,294