MBS, CRT Securities and MSR Related Assets (Composition of OTTI Charges) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Total OTTI losses	$ 0	$ 0	$ 0	$ (63)
OTTI reclassified from OCI	0	(618)	0	(969)
OTTI recognized in earnings	$ 0	$ (618)	$ 0	$ (1,032)

Amount before tax of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

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