Securitized Debt - Callable Debt (Detail) - Securitized Loans $ in Thousands	Jun. 30, 2018 USD ($)
Debt Instrument, Redemption [Line Items]
2018	$ 560,814
2019	360,602
2020	4,621,456
2021	3,197,192
2022	300,973
2023	142,144
Total	$ 9,183,181