INVESTMENT SECURITIES (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Fair Value of Available-for-Sale Investment Securities

The following table presents the amortized cost and fair value of the investment securities portfolio as of the dates indicated:



($ in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2018
Securities available-for-sale:
SBA loan pool securities	$	982	$	—	$	(12	)	$	970
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	493,757		7		(26,265		)	467,499
Non-agency residential mortgage-backed securities	651		14		(1		)	664
Non-agency commercial mortgage-backed securities	201,613		334		(1,226		)	200,721
Collateralized loan obligations	1,743,941		10,899		(101		)	1,754,739
Total securities available-for-sale	$	2,440,944	$	11,254	$	(27,605	)	$	2,424,593
December 31, 2017
Securities available-for-sale:
SBA loan pool securities	$	1,056	$	2	$	—		$	1,058
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	492,255		10		(15,336		)	476,929
Non-agency residential mortgage-backed securities	741		16		(1		)	756
Non-agency commercial mortgage-backed securities	305,172		5,339		—			310,511
Collateralized loan obligations	1,691,455		11,129		(266		)	1,702,318
Corporate debt securities	76,714		7,183		—			83,897
Total securities available-for-sale	$	2,567,393	$	23,679	$	(15,603	)	$	2,575,469

Proceeds from Sales and Calls of Securities and Associated Gross Gains and Losses

The following table presents proceeds from sales and calls of securities available-for-sale and the associated gross gains and losses realized through earnings upon the sales and calls of securities available-for-sale for the periods indicated:



	Three Months Ended March 31,
($ in thousands)	2018		2017
Gross realized gains on sales and calls of securities available-for-sale	$	5,241	$	3,356
Gross realized losses on sales and calls of securities available-for-sale	—		—
Net realized gains on sales and calls of securities available-for-sale	$	5,241	$	3,356
Proceeds from sales and calls of securities available-for-sale	$	287,517	$	378,539
Tax expense on sales and calls of securities available-for-sale	$	1,537	$	1,396

Summary of Investment Securities with Unrealized Losses

The following table summarizes the investment securities with unrealized losses by security type and length of time in a continuous unrealized loss position as of the dates indicated:



	Less Than 12 Months					12 Months or Longer					Total
($ in thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
March 31, 2018
Securities available-for-sale:
SBA loan pool securities	$	970	$	(12	)	$	—	$	—		$	970	$	(12	)
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	$	13,570	$	(281	)	$	449,970	$	(25,984	)	$	463,540	$	(26,265	)
Non-agency residential mortgage-backed securities	—		—			118		(1		)	118		(1		)
Non-agency commercial mortgage-backed securities	144,673		(1,226		)	—		—			144,673		(1,226		)
Collateralized loan obligations	66,749		(101		)	—		—			66,749		(101		)
Total securities available-for-sale	$	225,962	$	(1,620	)	$	450,088	$	(25,985	)	$	676,050	$	(27,605	)
December 31, 2017
Securities available-for-sale:
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	$	4,880	$	(35	)	$	470,092	$	(15,301	)	$	474,972	$	(15,336	)
Non-agency residential mortgage-backed securities	—		—			148		(1		)	148		(1		)
Collateralized loan obligations	104,334		(266		)	—		—			104,334		(266		)
Total securities available-for-sale	$	109,214	$	(301	)	$	470,240	$	(15,302	)	$	579,454	$	(15,603	)