Condensed Financial Information Of Parent Company Parent Company Information (Details 2) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net earnings	$ 85,647	$ 93,895	$ 82,168	$ 90,456	$ 352,166	$ 299,619	$ 168,905
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Decrease in other assets					6,441	48,172	49,498
Gain on sale of securities, net					(9,485)	(3,744)	(4,841)
Tax effect included in stockholders' equity of restricted stock vesting					(4,406)	(841)	(4,625)
Earned stock compensation					23,319	15,630	36,474
Net cash provided by operating activities					581,107	593,878	332,110
Net Cash Provided by (Used in) Investing Activities [Abstract]
Cash acquired in acquisitions, net of cash consideration paid					0	260,936	346,047
Payments to Acquire Available-for-sale Securities					(375,261)	(992,680)	(236,739)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Tax effect included in stockholders' equity of restricted stock vesting					4,406	841	4,625
Restricted stock surrendered					5,313	8,400	22,307
Cash dividends paid, net					(243,437)	(215,110)	(114,162)
Net cash provided by (used in) financing activities					400,629	131,879	(722,864)
Cash and Cash Equivalents, at Carrying Value	419,670				419,670	396,486	313,226	$ 147,422
Supplemental Cash Flow Information [Abstract]
shares of unvested restricted stock, respectively)	1,228				1,228	1,228
Parent Only
Condensed Financial Statements, Captions [Line Items]
Net earnings					352,166	299,619	168,905
Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract]
Decrease in other assets					96,668	145,709	25,515
Increase (Decrease) in Operating Liabilities					(17,311)	9,115	310
Gain on sale of securities, net					(405)	0	0
Tax effect included in stockholders' equity of restricted stock vesting					4,406	841	4,625
Earned stock compensation					23,319	14,994	41,099
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions					(100,956)	(91,198)	(38,935)
Net cash provided by operating activities					357,887	379,080	201,519
Net Cash Provided by (Used in) Investing Activities [Abstract]
Cash acquired in acquisitions, net of cash consideration paid					0	3,021	226,960
Payments to Acquire Available-for-sale Securities					995	0	0
Net Cash Provided by (Used in) Investing Activities, Continuing Operations					995	3,021	226,960
Net Cash Provided by (Used in) Financing Activities [Abstract]
Tax effect included in stockholders' equity of restricted stock vesting					(4,406)	(841)	(4,625)
Restricted stock surrendered					(33,244)	(8,400)	(22,307)
Increase (Decrease) in Notes Receivables					0	(50,000)	0
Cash dividends paid, net					(243,437)	(215,110)	(114,162)
Net cash provided by (used in) financing activities					(281,087)	(274,351)	(141,094)
Net Cash Provided by (Used in) Continuing Operations					77,795	107,750	287,385
Cash and Cash Equivalents, at Carrying Value	494,765				494,765	416,970	309,220	$ 21,835
Supplemental Cash Flow Information [Abstract]
shares of unvested restricted stock, respectively)	$ 0				$ 0	$ 797,433	$ 2,594,070