Consolidated Balance Sheets Parenthetical disclosures - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		$ 6,856,277	$ 6,757,250
Equity Securities, Cost		$ 93,564	$ 96,715
Preferred stock, shares authorized		10,000,000	10,000,000
Preferred stock, shares issued		5,000,000	5,000,000
Preferred stock, shares outstanding		5,000,000	5,000,000
Common stock, shares outstanding		24,718,815	24,930,526
Common Class A
Common stock, shares authorized		88,500,000	88,500,000
Common Stock, Shares, Issued		24,707,402	24,919,113
Common stock, shares outstanding		24,707,402	24,919,113
Common Class B
Common stock, shares authorized		1,500,000	1,500,000
Common Stock, Shares, Issued		11,413	11,413
Common stock, shares outstanding	[1]	11,413	11,413
Parent Company [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis		$ 24,936	$ 29,210
Equity Securities, Cost		$ 3,764	$ 2,942

[1] There is no established market for our Class B common stock, although it is convertible upon demand of the holder into Class A common stock on a share-for-share basis.