Securities Available-for-Sale (Comparative Summary of Mortgage-Backed Securities and Other Securities Available-for-Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 642,226	$ 771,935
Gross unrealized gains	7,816	9,663
Gross unrealized losses	9,830	10,359
Estimated fair value	640,212	771,239
Pass-through Certificates \| GSE
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	259,523	292,162
Gross unrealized gains	6,710	8,309
Gross unrealized losses	1,417	1,131
Estimated fair value	264,816	299,340
Real estate mortgage investment conduits (REMICs) \| GSE
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	348,813	408,328
Gross unrealized gains	1,081	1,314
Gross unrealized losses	8,378	9,192
Estimated fair value	341,516	400,450
Real estate mortgage investment conduits (REMICs) \| Non-GSE
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	844	1,060
Gross unrealized gains	0	0
Gross unrealized losses	33	34
Estimated fair value	811	1,026
Real estate mortgage investment conduits (REMICs) \| Mortgage Backed Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	609,180	701,550
Gross unrealized gains	7,791	9,623
Gross unrealized losses	9,828	10,357
Estimated fair value	607,143	700,816
Other securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	33,046	70,385
Gross unrealized gains	25	40
Gross unrealized losses	2	2
Estimated fair value	33,069	70,423
Other securities \| Equity investments-mutual funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	329	410
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	329	410
Other securities \| Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,717	69,975
Gross unrealized gains	25	40
Gross unrealized losses	2	2
Estimated fair value	$ 32,740	$ 70,013

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