Mortgage loans - Narrative (Details) (USD $) | 0 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 21 Months Ended | 0 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | 0 Months Ended | | 0 Months Ended | 1 Months Ended | 0 Months Ended | 1 Months Ended |
Sep. 30, 2014 | Jun. 27, 2014 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 15, 2014 | Jul. 31, 2014 | Jul. 10, 2014 | Jun. 27, 2014 | Jun. 04, 2014 | 2-May-14 | 1-May-14 | Mar. 11, 2014 | Feb. 28, 2014 | Jan. 31, 2014 | Jan. 28, 2014 | Jan. 02, 2014 | Dec. 24, 2013 | Dec. 19, 2013 | Nov. 22, 2013 | Nov. 12, 2013 | Oct. 21, 2013 | Sep. 30, 2013 | Sep. 19, 2013 | Aug. 26, 2013 | Aug. 12, 2013 | Aug. 06, 2013 | Jun. 25, 2013 | Apr. 05, 2013 | Mar. 21, 2013 | Feb. 14, 2013 | Feb. 12, 2013 | Jan. 23, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Dec. 31, 2013 | Jun. 27, 2014 | Jun. 04, 2014 | Sep. 30, 2014 | Oct. 24, 2014 | Oct. 31, 2014 | Oct. 24, 2014 | Oct. 31, 2014 | Oct. 31, 2014 | Oct. 31, 2014 |
loan | loan | property | property | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Nonperforming Financing Receivable [Member] | Performing Financing Receivable [Member] | Performing Financing Receivable [Member] | Performing Financing Receivable [Member] | Subsequent Event [Member] | Subsequent Event [Member] | Subsequent Event [Member] | Subsequent Event [Member] | Subsequent Event [Member] | Subsequent Event [Member] |
| property | loan | loan | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | Loans Receivable [Member] | | | Loans Receivable [Member] | Loans Receivable [Member] | Nonperforming Financing Receivable [Member] | Performing Financing Receivable [Member] |
| | | | | loan | | loan | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | Residential Mortgage [Member] | | | Residential Mortgage [Member] | Residential Mortgage [Member] | Loans Receivable [Member] | Loans Receivable [Member] |
| | | | | | | | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | loan | | | | loan | loan | Residential Mortgage [Member] | Residential Mortgage [Member] |
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Mortgage Loans on Real Estate [Line Items] | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Number of loans acquired | ' | ' | ' | ' | ' | ' | ' | 8,155 | ' | ' | ' | 1,243 | 46 | 1,116 | ' | ' | 664 | [1] | ' | | 70 | 3,421 | 66 | 650 | 2,204 | ' | ' | ' | 1,100 | 1,547 | 416 | 292 | ' | 1,562 | ' | 720 | 230 | 460 | ' | ' | ' | ' | 7,086 | ' | 8,531 | 879 | [2] | ' | | ' | ' | ' | 159 | ' | ' | ' |
Number of real estate properties directly acquired | ' | ' | ' | 34 | 190 | 40 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Unpaid principal balance of loans and real estate acquired | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | $1,900,000,000 | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Market value of underlying properties collateralizing loans acquired | ' | ' | ' | ' | ' | ' | ' | 1,994,200,000 | ' | ' | ' | 315,700,000 | 5,000,000 | 375,300,000 | ' | ' | 126,600,000 | | ' | | 8,200,000 | 791,700,000 | 7,000,000 | 93,600,000 | 530,100,000 | ' | ' | ' | 298,000,000 | 403,600,000 | 56,000,000 | 67,300,000 | ' | 185,200,000 | ' | 122,100,000 | 38,700,000 | 94,200,000 | ' | ' | ' | ' | 1,723,100,000 | ' | 1,795,200,000 | 271,100,000 | | ' | | ' | ' | ' | 31,600,000 | ' | ' | ' |
Purchase price of loans and real estate acquired | ' | ' | ' | ' | 1,100,000,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Number Of Loans To Be Acquired | ' | ' | ' | ' | ' | ' | ' | ' | ' | 20,362 | 246 | ' | ' | 2,377 | 3,191 | 78 | ' | | 915 | [3] | ' | ' | ' | ' | ' | 164 | 6,540 | 993 | ' | ' | ' | ' | 2,966 | ' | 321 | ' | ' | 762 | 244 | 460 | ' | ' | ' | ' | ' | ' | | 1,105 | [2] | ' | ' | ' | ' | ' | ' | ' |
Market value of underlying properties collateralizing loans to be acquired | ' | ' | ' | ' | ' | ' | ' | ' | ' | 4,562,700,000 | 29,700,000 | ' | ' | 296,100,000 | 891,600,000 | 8,700,000 | ' | | 180,000,000 | | ' | ' | ' | ' | ' | 18,300,000 | 1,542,100,000 | 137,300,000 | ' | ' | ' | ' | 790,200,000 | ' | 73,900,000 | ' | ' | 128,900,000 | 40,100,000 | 94,200,000 | ' | ' | ' | ' | ' | ' | | 331,600,000 | | ' | ' | ' | ' | ' | ' | ' |
Purchase price of loans acquired | ' | ' | ' | ' | 1,241,083,000 | 642,645,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | 21,000,000 | ' | ' | ' | ' | ' |
Market value of underlying properties collateralizing loans held for investment acquired | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | 271,100,000 | | ' | | ' | ' | ' | ' | ' | ' | ' |
Purchase price of loans held for investment acquired | ' | 144,600,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Amount accreted into interest income | ' | ' | 2,500,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Balance of performing loans held for investment | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | 204,346,000 | ' | ' | ' | ' | ' | ' |
Due diligence costs | ' | ' | ' | ' | ' | ' | 900,000 | 2,900,000 | 1,300,000 | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Number of real estate properties acquired through foreclosure | ' | ' | 1,113 | 43 | 2,657 | 77 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Transfer of mortgage loans to real estate owned | ' | ' | 189,900,000 | 6,200,000 | 410,913,000 | 10,598,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Unrealized Gain (Loss) From Conversion Of Mortgage Loan To Real Estate | ' | ' | 38,400,000 | 1,800,000 | 90,500,000 | 3,000,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Number of mortgage loans liquidated | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | 165 | 54 | 416 | 92 | ' | ' | | ' | | ' | ' | ' | ' | 934 | 164 | 770 |
Net realized gain on mortgage loans | ' | ' | 13,727,000 | 1,909,000 | 33,867,000 | 4,015,000 | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Period of clean pay history | '6 months | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' |
Proceeds from sale of loans | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | ' | | ' | | ' | ' | $164,000,000 | ' | ' | ' | ' |
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[1] | Includes 190 REOs. |
[2] | This acquisition consisted of a portfolio of re-performing loans. |
[3] | The remaining portion of this acquisition, consisting of 159 mortgage loans and REO properties, closed in October 2014. |