Fair Value - Recorded Amounts of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 565,135	$ 138,270
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	300	300
Agency Mortgage-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	536,148	127,693
Beneficial interest – FHLMC securitization
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	12,674
Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	565,135	138,270
Fair Value on Recurring Basis | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	300	300
Fair Value on Recurring Basis | FNMA and FHLB Agency Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	16,013	10,277
Fair Value on Recurring Basis | Agency Mortgage-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	536,148	127,693
Fair Value on Recurring Basis | Beneficial interest – FHLMC securitization
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	12,674
Fair Value Measurement Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	300	300
Fair Value Measurement Level 1 | Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	300	300
Fair Value Measurement Level 1 | Fair Value on Recurring Basis | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	300	300
Fair Value Measurement Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	552,161	137,970
Fair Value Measurement Level 2 | Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	552,161	137,970
Fair Value Measurement Level 2 | Fair Value on Recurring Basis | FNMA and FHLB Agency Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	16,013	10,277
Fair Value Measurement Level 2 | Fair Value on Recurring Basis | Agency Mortgage-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	536,148	$ 127,693
Fair Value Measurement Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	12,674
Fair Value Measurement Level 3 | Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	12,674
Fair Value Measurement Level 3 | Fair Value on Recurring Basis | Beneficial interest – FHLMC securitization
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale	$ 12,674