Securities (Rollforward of Other than Temporary Impairment, Credit Losses Recognized in Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance at beginning of period	$ 0	$ 0	$ 3,325
Credit-related impairment loss on debt securities for which an other-than-temporary impairment was not previously recognized	0	0	0
Additional increases to the amount of credit-related impairment loss on debt securities for which an other-than-temporary impairment was previously recognized	0	0	3,489
Reductions for securities for which a liquidation notice was received during the period	0	0	(4,868)
Reductions for securities for which the amount previously recognized in other comprehensive income was recognized in earnings because the entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost	0	0	(1,946)
Balance at end of period	$ 0	$ 0	$ 0