Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, value at Dec. 31, 2018	$ 9,906,000	$ 484,000	$ 5,000	$ 13,793,000	$ (3,433,000)	$ (943,000)
Balance, Common Stock, shares at Dec. 31, 2018			536,300
Net income (loss)	(179,000)				(179,000)
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	$ 779,000					779,000
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture	100
APIC, Share-based Payment Arrangement, Recognition and Exercise	$ 5,000			5,000
Proceeds from Issuance of Preferred Stock and Preference Stock	227,000
Stock Issued During Period, Shares, New Issues			11,400
Stock Issued During Period, Value, New Issues	190,000			190,000
Payments for Repurchase of Common Stock	0
Preferred dividends declared	(23,000)				(23,000)
Common dividends declared	(559,000)				(559,000)
Balance, value at Jun. 30, 2019	10,346,000	711,000	$ 5,000	13,988,000	(4,194,000)	(164,000)
Balance, Common Stock, shares at Jun. 30, 2019			547,800
Balance, value at Mar. 31, 2019	10,501,000	711,000	$ 5,000	13,795,000	(3,467,000)	(543,000)
Balance, Common Stock, shares at Mar. 31, 2019			536,300
Net income (loss)	(444,000)				(444,000)
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	$ 379,000					379,000
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture	100
APIC, Share-based Payment Arrangement, Recognition and Exercise	$ 3,000			3,000
Stock Issued During Period, Shares, New Issues			11,400
Stock Issued During Period, Value, New Issues	190,000			190,000
Preferred dividends declared	(13,000)				(13,000)
Common dividends declared	(270,000)				(270,000)
Balance, value at Jun. 30, 2019	10,346,000	711,000	$ 5,000	13,988,000	(4,194,000)	(164,000)
Balance, Common Stock, shares at Jun. 30, 2019			547,800
Balance, value at Dec. 31, 2019	$ 11,041,000	932,000	$ 5,000	13,893,000	(3,886,000)	97,000
Balance, Common Stock, shares at Dec. 31, 2019	540,900		540,900
Net income (loss)	$ (1,703,000)				(1,703,000)
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	$ 667,000					667,000
Shares Issued, Shares, Share-based Payment Arrangement, before Forfeiture	100
APIC, Share-based Payment Arrangement, Recognition and Exercise	$ 7,000			7,000
Stock Repurchased During Period, Shares	(12,200)
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 557,000
Stock Issued During Period, Shares, New Issues	26,700		26,700
Stock Issued During Period, Value, New Issues	$ 439,000		$ 1,000	438,000
Repurchase of common stock	(147,000)
Payments for Repurchase of Common Stock	147,000
Preferred dividends declared	(46,000)				(46,000)
Common dividends declared	(465,000)				(465,000)
Balance, value at Jun. 30, 2020	10,350,000	1,489,000	$ 6,000	14,191,000	(6,100,000)	764,000
Balance, Common Stock, shares at Jun. 30, 2020			555,500
Balance, value at Mar. 31, 2020	9,798,000	1,489,000	$ 6,000	14,334,000	(6,592,000)	561,000
Balance, Common Stock, shares at Mar. 31, 2020			567,700
Net income (loss)	718,000				718,000
Other comprehensive income (loss):
Unrealized Gains and (Losses), Net	203,000					203,000
APIC, Share-based Payment Arrangement, Recognition and Exercise	$ 4,000			4,000
Stock Repurchased During Period, Shares	(12,200)
Repurchase of common stock	$ (147,000)
Preferred dividends declared	(25,000)				(25,000)
Common dividends declared	(201,000)				(201,000)
Balance, value at Jun. 30, 2020	$ 10,350,000	$ 1,489,000	$ 6,000	$ 14,191,000	$ (6,100,000)	$ 764,000
Balance, Common Stock, shares at Jun. 30, 2020			555,500