Investments (Tables)

6 Months Ended

Jun. 30, 2015

Investments [Abstract]

Aggregate Values And Unrealized Gains And Losses Of Investment Securities

The amortized cost and fair value of investment securities classified as available for sale and held to maturity at June 30, 2015 and December 31, 2014, are as follows:

	June 30, 2015
(Dollars in thousands)	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities available for sale
U.S. Treasury	$	2,198,027	$	8,832	$	—	$	2,206,859
Government agency	774,962		1,667		385		776,244
Mortgage-backed securities	4,372,946		11,664		17,519		4,367,091
Total investment securities available for sale	$	7,345,935	$	22,163	$	17,904	$	7,350,194
	December 31, 2014
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
U.S. Treasury	$	2,626,900	$	2,922	$	152	$	2,629,670
Government agency	908,362		702		247		908,817
Mortgage-backed securities	3,628,187		16,964		11,847		3,633,304
Municipal securities	125		1		—		126
Total investment securities available for sale	$	7,163,574	$	20,589	$	12,246	$	7,171,917
	June 30, 2015
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities held to maturity
Mortgage-backed securities	$	351	$	14	$	—	$	365
	December 31, 2014
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Mortgage-backed securities	$	518	$	26	$	—	$	544

Investment Securities Maturity Information

The following table provides the amortized cost and fair value by contractual maturity. Expected maturities will differ from contractual maturities on certain securities because borrowers and issuers may have the right to call or prepay obligations with or without prepayment penalties. Repayments of mortgage-backed securities are dependent on the repayments of the underlying loan balances.

	June 30, 2015				December 31, 2014
(Dollars in thousands)	Cost		Fair value		Cost		Fair value
Investment securities available for sale
Non-amortizing securities maturing in:
One year or less	$	412,357	$	412,720	$	447,866	$	447,992
One through five years	2,560,632		2,570,383		3,087,521		3,090,621
Mortgage-backed securities	4,372,946		4,367,091		3,628,187		3,633,304
Total investment securities available for sale	$	7,345,935	$	7,350,194	$	7,163,574	$	7,171,917
Investment securities held to maturity
Mortgage-backed securities held to maturity	$	351	$	365	$	518	$	544

Securities Gains (Losses)

For each period presented, securities gains (losses) included the following:

	Three months ended June 30					Six months ended June 30
(Dollars in thousands)	2015			2014		2015			2014
Gross gains on sales of investment securities available for sale	$	151		$	—	$	5,286		$	—
Gross losses on sales of investment securities available for sale	(4		)	—		(13		)	—
Total net securities gain	$	147		$	—	$	5,273		$	—

Investment Securities With Unrealized Losses

The following table provides information regarding securities with unrealized losses as of June 30, 2015 and December 31, 2014.

	June 30, 2015
	Less than 12 months				12 months or more				Total
(Dollars in thousands)	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Investment securities available for sale:
Government agency	90,567		385		—		—		90,567		385
Mortgage-backed securities	1,872,344		12,736		296,170		4,783		2,168,514		17,519
Total	$	1,962,911	$	13,121	$	296,170	$	4,783	$	2,259,081	$	17,904
	December 31, 2014
	Less than 12 months				12 months or more				Total
	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Investment securities available for sale:
U.S. Treasury	$	338,612	$	151	$	1,015	$	1	$	339,627	$	152
Government agency	261,288		247		—		—		261,288		247
Mortgage-backed securities	573,374		1,805		831,405		10,042		1,404,779		11,847
Total	$	1,173,274	$	2,203	$	832,420	$	10,043	$	2,005,694	$	12,246