CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Supplemental disclosures of non-cash investing and financing activities
Common stock issued through the dividend reinvestment plan (in shares)							1,594	1,713
Common stock issued through the dividend reinvestment plan							$ 314	$ 290
Number of shares withheld to satisfy employees' tax withholding and other liabilities (in shares)							83,602	67,963
Shares withheld to satisfy employees' tax withholding and other liabilities, value							$ 15,961	$ 10,543
Stock issued during period, shares, share-based compensation, forfeited (in shares)							1,730
Stock issued during period, value, share-based compensation, forfeited							$ 305	679
Dividends declared but not paid	$ 213,651						213,651			$ 204,191
Change in redemption value of redeemable noncontrolling interest	113	$ 45	$ 224	$ 272	$ 291	$ 63
Increase (Decrease) in Derivative Liabilities							(17,824)
Cash flow hedge losses reclassified to earnings	(1,746)	(1,611)	(1,468)	(1,466)	(1,455)	(1,756)	(4,825)	$ (4,679)
Operating Lease, Right-of-Use Asset	99,270						99,270
Total lease liabilities	116,489						$ 116,489
Restricted Stock and Restricted Stock Converted From Performance Shares
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares)							150,359	187,010
Restricted Stock Converted From Performance Shares
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares)							73,072	88,297
Restricted stock
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares)							77,287	98,713
Fair value of shares issued							$ 15,145	$ 15,950
Stock issued during period, shares, share-based compensation, forfeited (in shares)							1,730	4,622
Common stock
Supplemental disclosures of non-cash investing and financing activities
Dividends declared but not paid	213,070			203,624			$ 213,070	$ 203,624
Accumulated earnings less dividends
Supplemental disclosures of non-cash investing and financing activities
Change in redemption value of redeemable noncontrolling interest	$ 113	$ 45	$ 224	$ 272	$ 291	$ 63	$ 382	$ 626
Accounting Standards Update 2016-02
Supplemental disclosures of non-cash investing and financing activities
Operating Lease, Right-of-Use Asset									$ 122,276
Total lease liabilities									$ 122,276