Variable Interest Entities - Principal Repayment of Mortgage Loans (Details) - Variable Interest Entity, Primary Beneficiary - Asset Backed Securities $ in Thousands	Jun. 30, 2015 USD ($)
Debt Instrument
Within one year	$ 394,635
One to three years	650,333
Three to five years	491,023
Greater than or equal to five years	1,444,766
Total	$ 2,980,757