Income Taxes Deferred Tax (Liabilities) Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Allowance for loan losses	$ 102,410	$ 80,554
Loan fee income	13,770	9,738
Other accruals not currently deductible	12,163	7,601
Share-based compensation expense	11,979	15,249
State income taxes	11,933	9,428
Net operating loss	4,406	8,641
Premises and equipment and other intangibles	1,748	1,344
Net unrealized losses on foreign currency translation	664	802
Research and development credit	324	324
Other	1,957	2,983
Deferred tax assets	161,354	136,664
Valuation allowance	(4,730)	(8,965)
Net deferred tax assets after valuation allowance	156,624	127,699
Deferred tax liabilities:
Nonmarketable securities	(35,721)	(31,800)
Derivative equity warrant assets	(31,955)	(19,090)
Net unrealized gains on available-for-sale securities	(10,199)	(29,600)
FHLB stock dividend	(1,247)	(1,230)
Other	(3,561)	0
Deferred tax liabilities	(82,683)	(81,720)
Net deferred tax (liabilities) assets	$ 73,941	$ 45,979