Commercial Mortgage Residual Interests (Schedule of Amounts Recognized as Unrealized Gains and/or Losses Recorded as Other Comprehensive Income and Other Than Temporary Valuation Impairments Recorded in Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commercial Mortgage Residual Interests [Abstract]
Unrealized gains (losses)	$ (585)	$ 875	$ 511
Other than temporary valuation impairment	$ 531	$ 256	$ 1,185