Preferred Stocks (Details) - USD ($)		12 Months Ended
	Apr. 01, 2017	Dec. 31, 2016	Dec. 31, 2017
Class of Stock [Line Items]
Preferred stocks		$ 15,000,000	$ 0
Payments for repurchase of redeemable preferred stock	$ 15,600,000
Redeemable preferred stock classified as long term debt	$ 300,000
Cumulative Preferred Stock, Par Value $100 Issuable in Series [Member]
Class of Stock [Line Items]
Authorized preferred cumulative shares (in shares)		500,000
Cumulative preferred shares, par value (in dollars per share)		$ 100.00
Preferred stock, series 4.50% [Member]
Class of Stock [Line Items]
Preferred stocks		$ 10,000,000	0
Preferred shares outstanding (in shares)		100,000
Preferred stock, $100 par value	4.50%	4.50%
Preferred stock, dividends per share, declared		$ 4.50
Preferred stock, redemption per share amount	$ 105
Preferred stock, series 4.70% [Member]
Class of Stock [Line Items]
Preferred stocks		$ 5,000,000	$ 0
Preferred shares outstanding (in shares)		50,000
Preferred stock, $100 par value	4.70%	4.70%
Preferred stock, dividends per share, declared		$ 4.70
Preferred stock, redemption per share amount	$ 102
Cumulative preferred stock A, without par value, issuable in series [Member]
Class of Stock [Line Items]
Authorized preferred cumulative shares (in shares)		1,000,000
Cumulative preference stock , without par value, issuable in series [Member]
Class of Stock [Line Items]
Authorized preferred cumulative shares (in shares)		500,000