Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 346,372	$ 312,276	$ 569,950	$ 474,339
Weighted average common shares outstanding - basic (in shares)	112,679	112,463	112,639	112,408
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	308	283	273	331
Weighted average common shares outstanding — diluted (in shares)	112,987	112,746	112,912	112,739
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 3.07	$ 2.78	$ 5.06	$ 4.22
Net income attributable to common shareholders - diluted (in dollars per share)	$ 3.07	$ 2.77	$ 5.05	$ 4.21