Investments (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Net change in unrealized gains (losses) from other trading account assets	$ (600,000)	$ (100,000)	$ (500,000)	$ 400,000
Net investment income	41,458,000	58,934,000	85,959,000	117,474,000
Gross unrealized losses related to high or highest quality securities	2,200,000		2,200,000		20,400,000
Gross unrealized losses related to other than high or highest quality securities	700,000		700,000		1,500,000
Gross unrealized losses representing declines in value of greater than 20%	0		0
Gross unrealized losses in a continuous loss position for less than six months	0		0		0
Twelve months or more Unrealized Losses	$ 1,737,000		$ 1,737,000		$ 1,621,000