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Mortgage Backed Securities Mortgage backed securities designated as AFS (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2014 | Mar. 31, 2013 | Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | $ 3,115,727 |  | $ 3,254,946
Available-for-sale MBS, Net Premium (Discount) | 812,735 |  | 758,950
Available-for-sale MBS, Amortized Cost | 3,928,462 |  | 4,013,896
Available-for-sale MBS, Gross Unrealized Gain | 52,704 | 45,114 |
Available-for-sale MBS, Gross Unrealized Loss | (49,882) | (69,566) |
Available-for-sale MBS, Fair Value | 3,931,284 |  | 3,989,444
Agency MBS [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 2,725,064 |  | 2,865,398
Available-for-sale MBS, Net Premium (Discount) | 621,260 |  | 627,047
Available-for-sale MBS, Amortized Cost | 3,346,324 |  | 3,492,445
Available-for-sale MBS, Gross Unrealized Gain | 29,673 | 26,792 |
Available-for-sale MBS, Gross Unrealized Loss | (47,806) | (63,976) |
Available-for-sale MBS, Fair Value | 3,328,191 |  | 3,455,261
Agency MBS [Member] | Residential Mortgage Backed Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 2,438,133 |  | 2,591,568
Available-for-sale MBS, Net Premium (Discount) | 139,899 |  | 154,220
Available-for-sale MBS, Amortized Cost | 2,578,032 |  | 2,745,788
Available-for-sale MBS, Gross Unrealized Gain | 6,708 | 6,104 |
Available-for-sale MBS, Gross Unrealized Loss | (45,438) | (59,742) |
Available-for-sale MBS, Fair Value | 2,539,302 |  | 2,692,150
Available-for-sale MBS, Weighted Average Coupon | 3.20% |  | 3.22%
Agency MBS [Member] | Commercial Mortgage Backed Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 286,931 |  | 273,830
Available-for-sale MBS, Net Premium (Discount) | 19,838 |  | 19,061
Available-for-sale MBS, Amortized Cost | 306,769 |  | 292,891
Available-for-sale MBS, Gross Unrealized Gain | 11,384 | 10,793 |
Available-for-sale MBS, Gross Unrealized Loss | (509) | (900) |
Available-for-sale MBS, Fair Value | 317,644 |  | 302,784
Available-for-sale MBS, Weighted Average Coupon | 5.23% |  | 5.07%
Agency MBS [Member] | CMBS IO [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 0 |  | 0
Available-for-sale MBS, notional balance for CMBS IO | 10,582,484 |  | 4,274,957
Available-for-sale MBS, Net Premium (Discount) | 461,523 |  | 453,766
Available-for-sale MBS, Amortized Cost | 461,523 |  | 453,766
Available-for-sale MBS, Gross Unrealized Gain | 11,581 | 9,895 |
Available-for-sale MBS, Gross Unrealized Loss | (1,859) | (3,334) |
Available-for-sale MBS, Fair Value | 471,245 |  | 460,327
Available-for-sale MBS, Weighted Average Coupon | 0.94% |  | 0.83%
Non-Agency MBS [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 390,663 |  | 389,548
Available-for-sale MBS, Net Premium (Discount) | 191,475 |  | 131,903
Available-for-sale MBS, Amortized Cost | 582,138 |  | 521,451
Available-for-sale MBS, Gross Unrealized Gain | 23,031 | 18,322 |
Available-for-sale MBS, Gross Unrealized Loss | (2,076) | (5,590) |
Available-for-sale MBS, Fair Value | 603,093 |  | 534,183
Non-Agency MBS [Member] | Residential Mortgage Backed Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 15,454 |  | 13,845
Available-for-sale MBS, Net Premium (Discount) | (7) |  | (338)
Available-for-sale MBS, Amortized Cost | 15,447 |  | 13,507
Available-for-sale MBS, Gross Unrealized Gain | 209 | 338 |
Available-for-sale MBS, Gross Unrealized Loss | (86) | (80) |
Available-for-sale MBS, Fair Value | 15,570 |  | 13,765
Available-for-sale MBS, Weighted Average Coupon | 4.42% |  | 4.61%
Non-Agency MBS [Member] | Commercial Mortgage Backed Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 375,209 |  | 375,703
Available-for-sale MBS, Net Premium (Discount) | (17,819) |  | (18,277)
Available-for-sale MBS, Amortized Cost | 357,390 |  | 357,426
Available-for-sale MBS, Gross Unrealized Gain | 19,448 | 15,366 |
Available-for-sale MBS, Gross Unrealized Loss | (842) | (3,511) |
Available-for-sale MBS, Fair Value | 375,996 |  | 369,281
Available-for-sale MBS, Weighted Average Coupon | 5.05% |  | 5.10%
Non-Agency MBS [Member] | CMBS IO [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Par Balance | 0 |  | 0
Available-for-sale MBS, notional balance for CMBS IO | 5,053,884 |  | 10,160,502
Available-for-sale MBS, Net Premium (Discount) | 209,301 |  | 150,518
Available-for-sale MBS, Amortized Cost | 209,301 |  | 150,518
Available-for-sale MBS, Gross Unrealized Gain | 3,374 | 2,618 |
Available-for-sale MBS, Gross Unrealized Loss | (1,148) | (1,999) |
Available-for-sale MBS, Fair Value | 211,527 |  | 151,137
Available-for-sale MBS, Weighted Average Coupon | 0.80% |  | 0.66%
Agency MBS [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 1,563,078 |  | 1,912,937
Available-for-sale MBS, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses | (29,207) | (43,543) |
Available-for-sale MBS, Number of Securities in Continuous Unrealized Loss Position for Less than One Year | 120 |  | 150
Available-for-sale MBS, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 767,744 |  | 670,402
Available-for-sale MBS, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses | (18,600) | (20,433) |
Available-for-sale MBS, Number of Securities in Continuous Unrealized Loss Position for Greater than or Equal to One Year | 80 |  | 67
Non-Agency MBS [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale MBS, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 126,578 |  | 162,558
Available-for-sale MBS, Continuous Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses | (1,990) | (5,435) |
Available-for-sale MBS, Number of Securities in Continuous Unrealized Loss Position for Less than One Year | 23 |  | 39
Available-for-sale MBS, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 1,676 |  | 6,310
Available-for-sale MBS, Continuous Unrealized Loss Position, 12 Months or Longer, Gross Unrealized Losses | $ (86) | $ (155) |
Available-for-sale MBS, Number of Securities in Continuous Unrealized Loss Position for Greater than or Equal to One Year | 5 |  | 6

X
- Definition The remaining amount of investment premium (discount), net, originally recognized at the purchase date of the instrument that has yet to be amortized (accreted). + References No definition available. + Details
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- Definition This item represents the current weighted-average gross interest rate earned on this type of MBS in the investment portfolio as of the period indicated. The gross interest rate of each MBS within the portfolio is weighted based on its current outstanding notional or par balance. The current outstanding notional or par balance for each MBS consists of the total of all principal balances remaining on the mortgage loans underlying each MBS. + References No definition available. + Details
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- Definition Notional balance for interest only securities owned by the Company. Interest only securities represent the right to receive excess interest payments and not principal cash flows based on the underlying unpaid principal balance (often referred to as the notional amount) of the underlying pool of mortgage loans. + References No definition available. + Details
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- Definition This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition Amount of unrealized gain before deducting unrealized loss on investments in debt securities classified as available-for-sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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- Definition Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale debt securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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- Definition Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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