Unsecured Borrowings - Unsecured Long-Term Borrowings after Hedging (Parenthetical) (Detail)	Mar. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Effective weighted average interest rates for unsecured long-term borrowings, after hedging - total	2.59%	2.87%
Effective weighted average interest rates for unsecured long-term borrowings, after hedging fixed rate obligations	3.82%	3.77%
Effective weighted average interest rates for unsecured long-term borrowings, after hedging - floating rate obligations	2.08%	2.48%