Schedule V - Valuation and Qualifying Accounts (Detail) - SEC Schedule, 12-09, Allowance, Loan and Lease Loss, Real Estate - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 21,333	$ 18,866	$ 12,490
Charged to costs and expenses	2,412	4,798	7,700
Written off	(4,585)	(2,331)	(1,324)
Change in estimate	0	0	0
Balance at end of year	$ 19,160	$ 21,333	$ 18,866