Notional Amounts of Swap Agreement, Weighted Average Interest Rates and Remaining Term (Detail) - Interest rate swap agreements - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 915,000	$ 2,501,000
Derivative, Notional Amount	$ 915,000
Weighted Average Fixed Rate	2.23%	2.02%
Remaining Term in Months	61 months	48 months
Less than 1 year
Derivative [Line Items]
Notional Amount	$ 200,000	$ 541,000
Weighted Average Fixed Rate	1.72%	1.70%
Remaining Term in Months	2 months	7 months
3 years to 4 years
Derivative [Line Items]
Notional Amount	$ 50,000	$ 295,000
Weighted Average Fixed Rate	1.55%	1.71%
Remaining Term in Months	40 months	45 months
4 years to 5 years
Derivative [Line Items]
Notional Amount	$ 175,000	$ 550,000
Weighted Average Fixed Rate	1.73%	2.18%
Remaining Term in Months	58 months	61 months
5 years to 7 years
Derivative [Line Items]
Notional Amount	$ 440,000	$ 390,000
Weighted Average Fixed Rate	2.63%	2.51%
Remaining Term in Months	87 months	85 months
7 years to 10 years
Derivative [Line Items]
Notional Amount	$ 50,000	$ 200,000
Weighted Average Fixed Rate	3.22%	2.94%
Remaining Term in Months	102 months	103 months