Financial Instruments and Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value of Debt	$ 15,676,592	$ 11,905,877
Fair Value of Debt	15,382,500	12,527,858
Credit Facilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value of Debt	52,522	184,255
Fair Value of Debt	52,522	184,255
Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value of Debt	13,045,081	9,660,570
Fair Value of Debt	12,693,738	10,228,715
Term Loans and Unsecured Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value of Debt	1,930,955	1,441,882
Fair Value of Debt	1,953,500	1,463,841
Secured Mortgages [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value of Debt	648,034	619,170
Fair Value of Debt	$ 682,740	$ 651,047