Loans Receivable and Allowance for Loan Losses (Composition of Loans Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Loans receivable and allowance for loan losses
30-59 Days	$ 87,210		$ 115,982
60-89 Days	19,874		26,750
90 Days or More	44,833		250,534
Total Past Due	151,917		393,266
Current	11,714,847		11,993,112
Total	11,866,764		12,386,378
Net unamortized premiums and deferred loan origination costs	49,171		55,688
Loans receivable	11,915,935		12,442,066
Allowance for loan losses	(113,600)	(118,600)	(139,000)	(143,000)	(143,900)	(145,501)
Loans receivable, net	11,802,335		12,303,066
Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	78,009		107,754
60-89 Days	17,635		24,154
90 Days or More	152		384
Total Past Due	95,796		132,292
Current	11,656,053		11,922,468
Total	11,751,849		12,054,760
Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	9,201		8,228
60-89 Days	2,239		2,596
90 Days or More	44,681		250,150
Total Past Due	56,121		260,974
Current	58,794		70,644
Total	114,915		331,618
Consumer and Other Loans
Loans receivable and allowance for loan losses
30-59 Days	1,698		3,177
60-89 Days	171		1,340
90 Days or More	6,323		5,948
Total Past Due	8,192		10,465
Current	236,804		229,216
Total	244,996		239,681
Allowance for loan losses	(9,426)	(9,540)	(8,824)	(7,327)	(7,605)	(6,316)
Consumer and Other Loans | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	1,698		3,177
60-89 Days	171		1,340
Total Past Due	1,869		4,517
Current	236,804		229,184
Total	238,673		233,701
Consumer and Other Loans | Non-accrual loans:
Loans receivable and allowance for loan losses
90 Days or More	6,323		5,948
Total Past Due	6,323		5,948
Current			32
Total	6,323		5,980
Consumer and Other Loans | Home equity lines of credit
Loans receivable and allowance for loan losses
30-59 Days	1,656		3,000
60-89 Days	159		1,321
90 Days or More	6,289		5,916
Total Past Due	8,104		10,237
Current	173,747		189,572
Total	181,851		199,809
Consumer and Other Loans | Home equity lines of credit | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	1,656		3,000
60-89 Days	159		1,321
Total Past Due	1,815		4,321
Current	173,747		189,540
Total	175,562		193,861
Consumer and Other Loans | Home equity lines of credit | Non-accrual loans:
Loans receivable and allowance for loan losses
90 Days or More	6,289		5,916
Total Past Due	6,289		5,916
Current			32
Total	6,289		5,948
Consumer and Other Loans | Other
Loans receivable and allowance for loan losses
30-59 Days	42		177
60-89 Days	12		19
90 Days or More	34		32
Total Past Due	88		228
Current	63,057		39,644
Total	63,145		39,872
Consumer and Other Loans | Other | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	42		177
60-89 Days	12		19
Total Past Due	54		196
Current	63,057		39,644
Total	63,111		39,840
Consumer and Other Loans | Other | Non-accrual loans:
Loans receivable and allowance for loan losses
90 Days or More	34		32
Total Past Due	34		32
Total	34		32
Mortgage loans (gross)
Loans receivable and allowance for loan losses
30-59 Days	85,512		112,805
60-89 Days	19,703		25,410
90 Days or More	38,510		244,586
Total Past Due	143,725		382,801
Current	11,478,043		11,763,896
Total	11,621,768		12,146,697
Mortgage loans (gross) | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	76,311		104,577
60-89 Days	17,464		22,814
90 Days or More	152		384
Total Past Due	93,927		127,775
Current	11,419,249		11,693,284
Total	11,513,176		11,821,059
Mortgage loans (gross) | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	9,201		8,228
60-89 Days	2,239		2,596
90 Days or More	38,358		244,202
Total Past Due	49,798		255,026
Current	58,794		70,612
Total	108,592		325,638
Mortgage loans (gross) | Residential
Loans receivable and allowance for loan losses
30-59 Days	76,176		96,302
60-89 Days	18,702		22,393
90 Days or More	31,869		234,378
Total Past Due	126,747		353,073
Current	6,955,477		7,684,203
Total	7,082,224		8,037,276
Allowance for loan losses	(49,332)	(56,552)	(80,337)	(83,424)	(78,788)	(89,267)
Mortgage loans (gross) | Residential | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	69,761		90,108
60-89 Days	16,463		20,154
90 Days or More			151
Total Past Due	86,224		110,413
Current	6,903,203		7,621,388
Total	6,989,427		7,731,801
Mortgage loans (gross) | Residential | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	6,415		6,194
60-89 Days	2,239		2,239
90 Days or More	31,869		234,227
Total Past Due	40,523		242,660
Current	52,274		62,815
Total	92,797		305,475
Mortgage loans (gross) | Residential | Full documentation interest-only
Loans receivable and allowance for loan losses
30-59 Days	17,683		29,476
60-89 Days	5,292		5,802
90 Days or More	9,268		78,271
Total Past Due	32,243		113,549
Current	960,988		1,268,652
Total	993,231		1,382,201
Mortgage loans (gross) | Residential | Full documentation interest-only | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	14,725		27,291
60-89 Days	5,115		5,220
Total Past Due	19,840		32,511
Current	942,958		1,249,462
Total	962,798		1,281,973
Mortgage loans (gross) | Residential | Full documentation interest-only | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	2,958		2,185
60-89 Days	177		582
90 Days or More	9,268		78,271
Total Past Due	12,403		81,038
Current	18,030		19,190
Total	30,433		100,228
Mortgage loans (gross) | Residential | Full documentation amortizing
Loans receivable and allowance for loan losses
30-59 Days	33,200		32,516
60-89 Days	5,424		8,068
90 Days or More	9,549		42,085
Total Past Due	48,173		82,669
Current	5,000,070		5,336,788
Total	5,048,243		5,419,457
Mortgage loans (gross) | Residential | Full documentation amortizing | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	32,652		31,189
60-89 Days	5,140		7,415
90 Days or More			151
Total Past Due	37,792		38,755
Current	4,994,848		5,325,944
Total	5,032,640		5,364,699
Mortgage loans (gross) | Residential | Full documentation amortizing | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	548		1,327
60-89 Days	284		653
90 Days or More	9,549		41,934
Total Past Due	10,381		43,914
Current	5,222		10,844
Total	15,603		54,758
Mortgage loans (gross) | Residential | Reduced documentation interest-only
Loans receivable and allowance for loan losses
30-59 Days	17,676		24,700
60-89 Days	5,482		5,787
90 Days or More	11,920		87,910
Total Past Due	35,078		118,397
Current	613,788		721,264
Total	648,866		839,661
Mortgage loans (gross) | Residential | Reduced documentation interest-only | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	15,566		22,635
60-89 Days	4,258		5,208
Total Past Due	19,824		27,843
Current	589,172		693,660
Total	608,996		721,503
Mortgage loans (gross) | Residential | Reduced documentation interest-only | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	2,110		2,065
60-89 Days	1,224		579
90 Days or More	11,920		87,910
Total Past Due	15,254		90,554
Current	24,616		27,604
Total	39,870		118,158
Mortgage loans (gross) | Residential | Reduced documentation amortizing
Loans receivable and allowance for loan losses
30-59 Days	7,617		9,610
60-89 Days	2,504		2,736
90 Days or More	1,132		26,112
Total Past Due	11,253		38,458
Current	380,631		357,499
Total	391,884		395,957
Mortgage loans (gross) | Residential | Reduced documentation amortizing | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	6,818		8,993
60-89 Days	1,950		2,311
Total Past Due	8,768		11,304
Current	376,225		352,322
Total	384,993		363,626
Mortgage loans (gross) | Residential | Reduced documentation amortizing | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	799		617
60-89 Days	554		425
90 Days or More	1,132		26,112
Total Past Due	2,485		27,154
Current	4,406		5,177
Total	6,891		32,331
Mortgage loans (gross) | Multi-family
Loans receivable and allowance for loan losses
30-59 Days	4,780		13,844
60-89 Days	506		1,327
90 Days or More	6,641		9,054
Total Past Due	11,927		24,225
Current	3,647,309		3,272,230
Total	3,659,236		3,296,455
Allowance for loan losses	(38,307)	(37,075)	(36,703)	(38,245)	(40,865)	(35,514)
Mortgage loans (gross) | Multi-family | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	4,351		12,740
60-89 Days	506		970
90 Days or More	152
Total Past Due	5,009		13,710
Current	3,644,376		3,270,206
Total	3,649,385		3,283,916
Mortgage loans (gross) | Multi-family | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	429		1,104
60-89 Days			357
90 Days or More	6,489		9,054
Total Past Due	6,918		10,515
Current	2,933		2,024
Total	9,851		12,539
Mortgage loans (gross) | Commercial real estate
Loans receivable and allowance for loan losses
30-59 Days	4,556		2,659
60-89 Days	495		1,690
90 Days or More			1,154
Total Past Due	5,051		5,503
Current	875,257		807,463
Total	880,308		812,966
Allowance for loan losses	(16,535)	(15,433)	(13,136)	(14,004)	(16,642)	(14,404)
Mortgage loans (gross) | Commercial real estate | Accruing loans:
Loans receivable and allowance for loan losses
30-59 Days	2,199		1,729
60-89 Days	495		1,690
90 Days or More			233
Total Past Due	2,694		3,652
Current	871,670		801,690
Total	874,364		805,342
Mortgage loans (gross) | Commercial real estate | Non-accrual loans:
Loans receivable and allowance for loan losses
30-59 Days	2,357		930
90 Days or More			921
Total Past Due	2,357		1,851
Current	3,587		5,773
Total	$ 5,944		$ 7,624