Investment Securities (Tables)

6 Months Ended

Jun. 30, 2016

Investment Securities

Schedule of amortized cost and fair values of investment securities

	Amortized		Gross Unrealized				Estimated
(Dollars in thousands)	Cost		Gains		Losses		Fair Value
June 30, 2016:
Held to maturity:
U.S. government-sponsored mortgage-backed securities	$	454,999	$	18,313	$	(246)	$	473,066
Trust preferred securities		992		—		—		992
Total	$	455,991	$	18,313	$	(246)	$	474,058
December 31, 2015:
Held to maturity:
U.S. government-sponsored mortgage-backed securities	$	492,143	$	11,092	$	(6,169)	$	497,066
Trust preferred securities		916		—		—		916
Total	$	493,059	$	11,092	$	(6,169)	$	497,982

Schedule of amortized cost and estimated fair value of investment securities by maturity

	Amortized		Estimated
(Dollars in thousands)	Cost		Fair Value
Held to maturity:
Due within 5 years	$	30	$	31
Due after 5 years through 10 years		—		—
Due after 10 years		455,961		474,027
Total	$	455,991	$	474,058

Schedule of realized gains and losses and proceeds from sales of securities held to maturity and trading

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(Dollars in thousands)	2016		2015		2016		2015
Proceeds from sales	$	3,122	$	2,503	$	3,122	$	5,083
Gross gains		190		240		190		476
Gross losses		—		—		—		—

Summary of investment securities in an unrealized loss position

	Less Than 12 Months				12 Months or Longer				Total
			Unrealized				Unrealized		Number of			Unrealized
Description of securities	Fair Value		Losses		Fair Value		Losses		Securities	Fair Value		Losses
(Dollars in thousands)
June 30, 2016
Mortgage-backed securities	$	1,421	$	1	$	33,499	$	245	13	$	34,920	$	246
December 31, 2015
Mortgage-backed securities	$	142,810	$	3,939	$	53,142	$	2,230	43	$	195,952	$	6,169

Cumulative roll forward of credit losses recognized in earnings for debt securities held and not intended to be sold

(Dollars in thousands)	2016		2015
Balance at January 1,	$	2,403	$	5,885
Credit losses on debt securities for which other-than-temporary impairment was not previously recognized		—		—
Credit losses on debt securities which were sold		—		(3,482)
Balance at June 30,	$	2,403	$	2,403

Schedule of components of accumulated other comprehensive loss, net of taxes, resulting from other-than-temporarily impaired securities

	June 30,
(Dollars in thousands)	2016		2015
Noncredit losses on other-than-temporarily impaired securities, net of taxes	$	101	$	176