Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 339,798	$ 346,372	$ 591,136	$ 569,950
Weighted average common shares outstanding - basic (in shares)	112,923	112,679	112,878	112,639
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	294	308	300	273
Weighted average common shares outstanding — diluted (in shares)	113,217	112,987	113,178	112,912
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 3.01	$ 3.07	$ 5.24	$ 5.06
Net income attributable to common shareholders - diluted (in dollars per share)	$ 3.00	$ 3.07	$ 5.22	$ 5.05