QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenues	$ 2,663,606	$ 2,263,228	$ 2,457,575	$ 2,779,958	$ 3,136,700	$ 3,393,890	$ 2,960,529	$ 3,102,077	$ 10,164,367	$ 12,593,196	$ 12,173,907
Operating income	487,314	482,151	476,146	468,742	471,865	495,534	448,366	419,699	1,914,353	1,835,464	1,391,771
Net income	320,251	309,155	311,963	337,208	292,888	313,916	282,179	266,049	1,278,577	1,155,032	593,519
Net income available to common shareholders	$ 319,976	$ 308,880	$ 311,688	$ 336,933	$ 292,613	$ 312,984	$ 280,773	$ 264,233	$ 1,277,477	$ 1,150,603	$ 387,074
Earnings per share- Basic	$ 0.77	$ 0.75	$ 0.75	$ 0.82	$ 0.71	$ 0.76	$ 0.68	$ 0.65	$ 3.09	$ 2.80	$ 1.30
Earnings per share- Diluted	$ 0.77	$ 0.74	$ 0.75	$ 0.81	$ 0.70	$ 0.75	$ 0.68	$ 0.64	$ 3.07	$ 2.78	$ 1.29