Investment Securities Held-to-Maturity (Tables)

12 Months Ended

Dec. 31, 2014

Text Block [Abstract]

Summary of Held-to-Maturity Securities

	December 31, 2014								December 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
(dollars in thousands)
U.S. Government Sponsored Enterprise	$	251,617	$	2,707	$	249	$	254,075	$	291,779	$	185	$	5,043	$	286,921
U.S. Government Sponsored Enterprise Mortgage-Backed Securities		1,155,175		11,185		6,832		1,159,528		1,196,105		2,239		20,816		1,177,528
Total	$	1,406,792	$	13,892	$	7,081	$	1,413,603	$	1,487,884	$	2,424	$	25,859	$	1,464,449

Company's Securities Held-to-Maturity

The following table shows the maturity distribution of the Company’s securities held-to-maturity at December 31, 2014.

	Amortized Cost		Fair Value
(dollars in thousands)
Within one year	$	3,837	$	3,912
After one but within five years		1,095,478		1,098,957
After five but within ten years		305,690		308,892
More than ten years		1,787		1,842
Total	$	1,406,792	$	1,413,603

Unrealized Market Loss of Securities

The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2014. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 34 and 48 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 303 holdings at December 31, 2014.

	December 31, 2014
	Less Than 12 Months				12 Months or Longer				Total
Temporarily Impaired Investments	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
(dollars in thousands)
U.S. Government Sponsored Enterprises	$	22,414	$	25	$	14,776	$	224	$	37,190	$	249
U.S. Government Agency and Sponsored
Enterprise Mortgage-Backed Securities		194,119		1,678		308,526		5,154		502,645		6,832
Total temporarily impaired securities	$	216,533	$	1,703	$	323,302	$	5,378	$	539,835	$	7,081

The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2013. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 191 and 13 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 300 holdings at December 31, 2013.

	December 31, 2013
	Less Than 12 Months				12 Months or Longer				Total
Temporarily Impaired Investments	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
(dollars in thousands)
U.S. Government Sponsored Enterprises	$	232,535	$	5,043	$	—	$	—	$	232,535	$	5,043
U.S. Government Agency and Sponsored
Enterprise Mortgage-Backed Securities		931,180		18,654		80,362		2,162		1,011,542		20,816
Total temporarily impaired securities	$	1,163,715	$	23,697	$	80,362	$	2,162	$	1,244,077	$	25,859