Condensed Financial Information Of Parent Company Parent Company Information (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Investment Income, Dividend									$ 1,866	$ 2,575	$ 4,046
Interest Expense	$ 21,641	$ 19,276	$ 17,071	$ 14,957	$ 13,468	$ 13,220	$ 13,297	$ 14,636	72,945	54,621	60,592
Income Tax Expense (Benefit)	(56,440)	(37,945)	54,902	47,626	$ (49,716)	$ (48,479)	$ (49,726)	$ (57,849)	(196,913)	(205,770)	(180,517)
Net earnings	$ 84,037	$ 101,466	$ 93,647	$ 78,668					357,818	352,166	299,619
Parent Only
Condensed Financial Statements, Captions [Line Items]
Other Income									3,393	2,146	1,458
Investment Income, Dividend									265,000	259,000	214,000
Total Income									268,393	261,146	215,458
Interest Expense									5,519	4,816	4,279
Operating Expenses									8,273	7,732	6,983
Total Expenses									13,792	12,548	11,262
Net earnings from continuing operations									254,601	248,598	204,196
Income Tax Expense (Benefit)									19,957	2,612	4,225
Income Loss From Continuing Operations Before Income Loss From Equity Method Investments									274,558	251,210	208,421
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions									83,260	100,956	91,198
Net earnings									$ 357,818	$ 352,166	$ 299,619