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Investments (Number of Securities in an Unrealized Unrecognized Loss Position) (Details) $ in Thousands	Mar. 31, 2017 USD ($) Securities	Dec. 31, 2016 USD ($) Securities
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Unrealized Unrecognized Loss	$ 8,326	$ 16,215
Eighty Percent to Ninety-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	304	456
Unrealized Unrecognized Loss	$ 8,326	$ 16,215
Sixty Percent to Seventy-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Forty Percent to Fifty-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Twenty Percent to Thirty-Nine Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Zero Percent to Nineteen Percent [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Number Of Securities In An Unrealized/Unrecognized Loss Position | Securities	0	0
Unrealized Unrecognized Loss	$ 0	$ 0
Held-to-maturity Securities [Member]
Schedule of Available-for-sale and held-to-maturity Securities [Line Items]
Unrealized Unrecognized Loss	$ 100	$ 200

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- Definition

This item contains disclosure of the number of available-for-sale and held-to-maturity securities determined to be in an unrealized/unrecognized loss position.

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This item represents the sum of (i) the excess of amortized cost over fair value for available-for-sale securities that are in a loss position and (ii) the market fluctuations on held-to-maturity securities from the later of (a) the date a security is designated as held-to-maturity; or (b) the date that an other-than-temporary impairment charge is recognized on a held-to-maturity security for securities that are in an unrecognized loss position.

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