Fair Value Measurements - Summary of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Loans held for sale	$ 2,499,111	$ 1,072,116
Pledged securities	72,190	67,719
Derivative assets	11,678	14,535
Liabilities
Derivative liabilities	1,333	4,877
Fair Value
Assets
Loans held for sale	2,499,111	1,072,116
Pledged securities	72,190	67,719
Derivative assets	11,678	14,535
Total financial assets	2,958,643	1,506,896
Liabilities
Derivative liabilities	1,333	4,877
Recurring
Assets
Loans held for sale	2,499,111	1,072,116
Pledged securities	72,190	67,719
Derivative assets	11,678	14,535
Total financial assets	2,582,979	1,154,370
Liabilities
Derivative liabilities	1,333	4,877
Total financial liabilities	1,333	4,877
Level 1 | Recurring
Assets
Pledged securities	72,190	67,719
Total financial assets	72,190	67,719
Level 2 | Recurring
Assets
Loans held for sale	2,499,111	1,072,116
Total financial assets	2,499,111	1,072,116
Level 3 | Recurring
Assets
Derivative assets	11,678	14,535
Total financial assets	11,678	14,535
Liabilities
Derivative liabilities	1,333	4,877
Total financial liabilities	$ 1,333	$ 4,877