Real Estate and Lending Activities - Schedule of Revenue from External Customers by Geographic Areas (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue	$ 126,300	$ 99,801	$ 261,299	$ 195,762
Revenue [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 261,299	$ 195,762
Percentage of Total Revenue			100.00%	100.00%
Revenue [Member] | Texas [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 48,256	$ 42,689
Percentage of Total Revenue			18.50%	21.80%
Revenue [Member] | California [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 33,187	$ 33,065
Percentage of Total Revenue			12.70%	16.90%
Revenue [Member] | All Other States [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 129,896	$ 85,620
Percentage of Total Revenue			49.70%	43.70%
Revenue [Member] | United States [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 211,339	$ 161,374
Percentage of Total Revenue			80.90%	82.40%
Revenue [Member] | Germany [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 47,745	$ 32,212
Percentage of Total Revenue			18.30%	16.50%
Revenue [Member] | United Kingdom, Italy, and Spain [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 2,215	$ 2,176
Percentage of Total Revenue			0.80%	1.10%
Revenue [Member] | International [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers By Geographic Area [Line Items]
Total Revenue			$ 49,960	$ 34,388
Percentage of Total Revenue			19.10%	17.60%