Notes Payable, Other and Short-Term Borrowings - Carrying Amounts and Estimated Fair Values of Company's Senior Notes (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	$ 1,295,139	$ 1,040,064
Estimated fair value of the Company's long-term debt	1,343,304	1,093,799
5.125% Senior Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	255,308	298,688
Estimated fair value of the Company's long-term debt	260,154	311,100
5.375% Senior Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	446,244	445,247
Estimated fair value of the Company's long-term debt	476,730	482,099
3.750% Senior Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	296,701	296,129
Estimated fair value of the Company's long-term debt	300,330	$ 300,600
4.375% Senior Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	296,886
Estimated fair value of the Company's long-term debt	$ 306,090