Investments - Narrative (Details)		10 Months Ended	12 Months Ended
	Nov. 01, 2016 USD ($)	Oct. 31, 2016	Dec. 31, 2016 USD ($) member	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of Investment Committee members required to authorize investment | member			2
Fair Value			$ 181,361,000	$ 198,312,000
Realized gains (losses) on sale of securities			795,000	5,311,000	$ (833,000)
Proceeds from sales of securities			197,548,000	385,695,000	83,239,000
Maturities of securities			185,000,000	410,000,000
Gross Unrealized Losses			1,886,000	1,117,000
Other-than-temporary impairment losses			0	0	$ 1,295,000
Debt securities, fair value			139,132,000
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value				184,740,000
Gross Unrealized Losses				79,000
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value			139,132,000	6,292,000
Gross Unrealized Losses			1,769,000	981,000
Debt securities, fair value			139,100,000
Preferred stock
Schedule of Available-for-sale Securities [Line Items]
Fair Value			36,593,000	208,000
Gross Unrealized Losses			111,000	$ 57,000
Short-term bond
Schedule of Available-for-sale Securities [Line Items]
Fair Value			4,226,000
Gross Unrealized Losses			6,000
Sears Holdings Corp or affiliates | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Debt securities, fair value			9,400,000
Sears Holdings Corp or affiliates | Preferred stock
Schedule of Available-for-sale Securities [Line Items]
Other marketable securities, noncurrent			$ 200,000
Corporate debt securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent			15.00%
Cash, investment grade cash equivalents or U.S. treasury securities | Minimum
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent	25.00%	50.00%
Other aggregated investments | Minimum | Securities of any one issuer (excluding the U.S. Government)
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent			10.00%
Other aggregated investments | Maximum | Securities of any one issuer (excluding the U.S. Government)
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent			15.00%
Other aggregated investments | Maximum | Single Issuer, Exchange-Traded Common Equities
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent	5.00%
Common stock investments | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations, amount	$ 100,000,000.0
Common, preferred or other equity investments | Maximum
Schedule of Available-for-sale Securities [Line Items]
Investments, target portfolio allocations percent	25.00%
Investor | Fairholme Capital Management, L.L.C.
Schedule of Available-for-sale Securities [Line Items]
Common stock ownership percentage			32.90%