Investment Securities (Tables)

6 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and the fair value of securities available-for-sale

The following tables present the amortized cost, gross unrealized gains, gross unrealized losses and the fair value for securities available-for-sale at March 31, 2018 and September 30, 2017:

	March 31, 2018
	Amortized cost		Gross unrealized gains	Gross unrealized (losses)		Fair value
			(In thousands)
U.S. government and agency obligations	$	54,799	26	(928	)	$	53,897
Mortgage-backed securities and collateralized mortgage obligations	754,862		406	(20,069	)	735,199
Municipal obligations	1,295		—	—		1,295
Corporate debt securities	54,490		270	(748	)	54,012
Trust preferred securities	5,000		—	(348	)	4,652
Equity securities	2,328		830	—		3,158
	$	872,774	1,532	(22,093	)	$	852,213

	September 30, 2017
	Amortized cost		Gross unrealized gains	Gross unrealized (losses)		Fair value
			(In thousands)
U.S. government and agency obligations	$	24,954	35	(116	)	$	24,873
Mortgage-backed securities and collateralized mortgage obligations	479,927		652	(7,088	)	473,491
Municipal obligations	1,357		—	—		1,357
Corporate debt securities	49,489		536	(532	)	49,493
Trust preferred securities	5,000		—	(292	)	4,708
Equity securities	2,482		826	(54	)	3,254
	$	563,209	2,049	(8,082	)	$	557,176

Schedule of securities by contractual maturity

The table below presents the amortized cost and fair value of debt securities held-to-maturity at March 31, 2018 by contractual maturity. Expected maturities may differ from contractual maturities due to prepayment or early call privileges of the issuer.

	March 31, 2018
	Amortized cost		Fair value
	(In Thousands)
More than five years to ten years	$	13,402	$	13,159
	13,402		13,159
Mortgage-backed securities and collateralized mortgage obligations	240,729		232,318
	$	254,131	$	245,477

The table below presents the amortized cost and fair value of debt securities available-for-sale at March 31, 2018 by contractual maturity excluding equity securities. Expected maturities may differ from contractual maturities due to prepayment or early call privileges of the issuer.

	March 31, 2018
	Amortized cost		Fair value
	(In thousands)
One year or less	$	1,104	$	1,105
More than one year to five years	45,121		44,385
More than five years to ten years	59,359		59,204
More than ten years	10,000		9,162
	$	115,584	$	113,856
Mortgage-backed securities and collateralized mortgage obligations	754,862		735,199
	$	870,446	$	849,055

Schedule of available-for-sale securities reported in a continuous unrealized loss position

The following tables summarize the fair value and gross unrealized losses of those securities that reported an unrealized loss at March 31, 2018 and September 30, 2017 and if the unrealized loss position was continuous for the twelve months prior to March 31, 2018 and September 30, 2017:

	March 31, 2018
	Less than 12 months				12 months or longer			Total
	Fair Value		Gross unrealized (losses)		Fair value	Gross unrealized (losses)		Fair value	Gross unrealized (losses)
	(In thousands)
U.S. government and agency obligations	$	44,092	(722	)	4,774	(206	)	48,866	$	(928	)
Mortgage-backed securities and collateralized mortgage obligations	485,994		(11,572	)	156,550	(8,497	)	642,544	(20,069		)
Corporate debt securities	14,894		(98	)	9,351	(650	)	24,245	(748		)
Trust preferred securities	4,652		(348	)	—	—		4,652	(348		)
	$	549,632	(12,740	)	170,675	(9,353	)	720,307	$	(22,093	)

	September 30, 2017
	Less than 12 months				12 months or longer			Total
	Fair Value		Gross unrealized (losses)		Fair value	Gross unrealized (losses)		Fair value	Gross unrealized (losses)
	(In thousands)
U.S. government and agency obligations	$	14,831	(116	)	—	—		14,831	$	(116	)
Mortgage-backed securities and collateralized mortgage obligations	329,554		(5,346	)	49,695	(1,742	)	379,249	(7,088		)
Corporate debt securities	9,824		(176	)	9,644	(356	)	19,468	(532		)
Trust preferred securities	—		—		4,708	(292	)	4,708	(292		)
Equity securities	98		(54	)	—	—		98	(54		)
	$	354,307	(5,692	)	64,047	(2,390	)	418,354	$	(8,082	)

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and the fair value of securities held-to-maturity

The following tables present the amortized cost, gross unrealized gains, gross unrealized losses and the fair value for securities held-to-maturity at March 31, 2018 and September 30, 2017:

	March 31, 2018
	Amortized cost		Gross unrealized gains	Gross unrealized (losses)		Fair value
	(In thousands)
U.S. government and agency obligations	$	13,402	—	(243	)	$	13,159
Mortgage-backed securities and collateralized mortgage obligations	240,729		530	(8,941	)	232,318
	$	254,131	530	(9,184	)	$	245,477

	September 30, 2017
	Amortized cost		Gross unrealized gains	Gross unrealized (losses)		Fair value
	(In thousands)
U.S. government and agency obligations	$	3,407	—	(7	)	$	3,400
Mortgage-backed securities and collateralized mortgage obligations	129,532		—	(1,110	)	128,422
	$	132,939	—	(1,117	)	$	131,822

Schedule of held-to-maturity securities reported in a continuous unrealized loss position

The following tables summarize the fair value and gross unrealized losses of those securities that reported an unrealized loss at March 31, 2018 and September 30, 2017 and if the unrealized loss position was continuous for the twelve months prior to March 31, 2018 and September 30, 2017:

	March 31, 2018
	Less than 12 months				12 months or longer			Total
	Fair Value		Gross unrealized (losses)		Fair value	Gross unrealized (losses)		Fair value	Gross unrealized (losses)
	(In thousands)
U.S. government and agency obligations	$	8,160	(243	)	—	—		8,160	$	(243	)
Mortgage-backed securities and collateralized mortgage obligations	139,886		(4,300	)	69,110	(4,641	)	208,996	(8,941		)
	$	148,046	(4,543	)	69,110	(4,641	)	217,156	$	(9,184	)

	September 30, 2017
	Less than 12 months				12 months or longer			Total
	Fair Value		Gross unrealized (losses)		Fair value	Gross unrealized (losses)		Fair value	Gross unrealized (losses)
	(In thousands)
U.S. government and agency obligations	$	—	—		3,400	(7	)	3,400	$	(7	)
Mortgage-backed securities and collateralized mortgage obligations	29,965		(349	)	96,076	(761	)	126,041	(1,110		)
	$	29,965	(349	)	99,476	(768	)	129,441	$	(1,117	)