Investments (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2016 and December 31, 2015, are as follows:

	March 31, 2016
(Dollars in thousands)	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities available for sale
U.S. Treasury	$	1,538,907	$	2,308	$	—	$	1,541,215
Government agency	355,488		669		—		356,157
Mortgage-backed securities	4,693,313		37,375		3,406		4,727,282
Equity securities	50,066		2,314		285		52,095
Other	10,615		—		75		10,540
Total investment securities available for sale	$	6,648,389	$	42,666	$	3,766	$	6,687,289
	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
Other	10,615		45		—		10,660
Total investment securities available for sale	$	6,885,797	$	6,367	$	30,871	$	6,861,293
	March 31, 2016
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities held to maturity
Mortgage-backed securities	$	194	$	9	$	—	$	203
	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.

	March 31, 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	$	1,554,483	$	1,556,414	$	1,255,714	$	1,255,094
One through five years	339,912		340,958		919,086		918,448
Five through 10 years	8,500		8,500		8,500		8,500
Over 10 years	2,115		2,040		2,115		2,160
Mortgage-backed securities	4,693,313		4,727,282		4,692,447		4,668,198
Equity securities	50,066		52,095		7,935		8,893
Total investment securities available for sale	$	6,648,389	$	6,687,289	$	6,885,797	$	6,861,293
Investment securities held to maturity
Mortgage-backed securities held to maturity	$	194	$	203	$	255	$	265

Securities Gains (Losses)

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

	Three months ended March 31
(Dollars in thousands)	2016			2015
Gross gains on sales of investment securities available for sale	$	4,933		$	5,135
Gross losses on sales of investment securities available for sale	(305		)	(9		)
Total securities gains	$	4,628		$	5,126

Investment Securities With Unrealized Losses

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

	March 31, 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:
Mortgage-backed securities	$	417,711	$	1,071	$	291,021	$	2,335	$	708,732	$	3,406
Equity securities	13,037		285		—		—		13,037		285
Other	2,040		75		—		—		2,040		75
Total	$	432,788	$	1,431	$	291,021	$	2,335	$	723,809	$	3,766
	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