Investment in Securities, Summary of Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	$ 17,642,000	$ 13,578,000	$ 17,642,000	$ 13,578,000	$ 17,898,000
Gross unrealized gains	14,420,000	23,851,000	14,420,000	23,851,000	14,709,000
Gross unrealized losses	0	0	0	0	0
Fair value	32,062,000	37,429,000	32,062,000	37,429,000	32,607,000
Unrealized changes to fair value net of taxes included in other comprehensive income	(2,766,000)	(255,000)	(183,000)	(722,000)
Proceeds from sale of investment available for sale	100,000	19,000	408,000	51,000
Gross realized gains on sale of investment available for sale	2,000	2,000	4,000	5,000
Gross realized losses on sale of investment available for sale	0	0	0	0
Common Stock [Member]
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	17,642,000	13,578,000	17,642,000	13,578,000	17,898,000
Gross unrealized gains	14,420,000	23,851,000	14,420,000	23,851,000	14,709,000
Gross unrealized losses	0	0	0	0	0
Fair value	$ 32,062,000	$ 37,429,000	$ 32,062,000	$ 37,429,000	$ 32,607,000