Investments (Tables)

9 Months Ended

Sep. 30, 2016

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 September 30, 2016 and December 31, 2015, are as follows:

	September 30, 2016
(Dollars in thousands)	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities available for sale
U.S. Treasury	$	1,547,501	$	2,030	$	1	$	1,549,530
Government agency	169,609		250		—		169,859
Mortgage-backed securities	4,487,083		44,570		3,283		4,528,370
Equity securities	88,526		4,653		168		93,011
Corporate bonds	41,363		582		—		41,945
Other	2,115		—		15		2,100
Total investment securities available for sale	$	6,336,197	$	52,085	$	3,467	$	6,384,815
	December 31, 2015
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
U.S. Treasury	$	1,675,996	$	4	$	1,118	$	1,674,882
Government agency	498,804		230		374		498,660
Mortgage-backed securities	4,692,447		5,120		29,369		4,668,198
Equity securities	7,935		968		10		8,893
Corporate bonds	8,500		—		—		8,500
Other	2,115		45		—		2,160
Total investment securities available for sale	$	6,885,797	$	6,367	$	30,871	$	6,861,293
	September 30, 2016
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities held to maturity
Mortgage-backed securities	$	125	$	8	$	—	$	133
	December 31, 2015
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Mortgage-backed securities	$	255	$	10	$	—	$	265

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. Equity securities do not have a stated maturity date.

	September 30, 2016				December 31, 2015
(Dollars in thousands)	Cost		Fair value		Cost		Fair value
Investment securities available for sale
Non-amortizing securities maturing in:
One year or less	$	1,367,521	$	1,369,117	$	1,255,714	$	1,255,094
One through five years	349,589		350,272		919,086		918,448
Five through 10 years	41,363		41,945		8,500		8,500
Over 10 years	2,115		2,100		2,115		2,160
Mortgage-backed securities	4,487,083		4,528,370		4,692,447		4,668,198
Equity securities	88,526		93,011		7,935		8,893
Total investment securities available for sale	$	6,336,197	$	6,384,815	$	6,885,797	$	6,861,293
Investment securities held to maturity
Mortgage-backed securities held to maturity	$	125	$	133	$	255	$	265

Securities Gains (Losses)

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

	Three months ended September 30					Nine months ended September 30
(Dollars in thousands)	2016			2015		2016			2015
Gross gains on sales of investment securities available for sale	$	452		$	5,564	$	17,940		$	10,850
Gross losses on sales of investment securities available for sale	(100		)	—		(431		)	(13		)
Total securities gains	$	352		$	5,564	$	17,509		$	10,837

Investment Securities With Unrealized Losses

The following table provides information regarding securities with unrealized losses as of September 30, 2016 and December 31, 2015.

	September 30, 2016
	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:
U.S. Treasury	$	9,995	$	1	$	—	$	—	$	9,995	$	1
Mortgage-backed securities	356,758		1,111		289,161		2,172		645,919		3,283
Equity securities	23,131		168		—		—		23,131		168
Other	2,100		15		—		—		2,100		15
Total	$	391,984	$	1,295	$	289,161	$	2,172	$	681,145	$	3,467
	December 31, 2015
	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	$	1,539,637	$	1,118	$	—	$	—	$	1,539,637	$	1,118
Government agency	229,436		374		—		—		229,436		374
Mortgage-backed securities	3,570,470		23,275		280,126		6,094		3,850,596		29,369
Equity securities	728		10		—		—		728		10
Total	$	5,340,271	$	24,777	$	280,126	$	6,094	$	5,620,397	$	30,871