Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 40,714	$ 27,896
Cash flows from investing activities:
Sale of debt securities	1,999	13,456
Maturities of debt securities	7,810	7,174
Purchase of debt securities	(3,366)	(14,974)
Purchase of equity securities	(998)	0
Sale of equity securities	358	0
Maturities of equity securities	302	0
Purchase of long-term investments	0	(22,400)
Investments in real estate ventures	(533)	(1,436)
Distributions from investments in real estate ventures	219	0
Increase in cash surrender value of life insurance policies	(36)	(49)
(Increase) decrease in restricted assets	(4)	2,104
Issuance of notes receivable	0	(1,500)
Proceeds from sale of fixed assets	0	2
Capital expenditures	(3,987)	(4,588)
Repayments of notes receivable	32	0
Pay downs of investment securities	446	864
Investments in real estate, net	(355)	(70)
Net cash provided by (used in) investing activities	1,887	(21,417)
Cash flows from financing activities:
Proceeds from issuance of debt	0	850,000
Deferred financing costs	0	(19,200)
Repayments of debt	(490)	(835,697)
Borrowings under revolver	55,170	39,956
Repayments on revolver	(61,728)	(68,305)
Dividends and distributions on common stock	(57,187)	(52,358)
Proceeds from issuance of Vector common stock	0	43,230
Net cash used in financing activities	(64,235)	(42,374)
Net decrease in cash, cash equivalents and restricted cash	(21,634)	(35,895)
Cash, cash equivalents and restricted cash, beginning of period	310,937	398,608
Cash, cash equivalents and restricted cash, end of period	$ 289,303	$ 362,713