Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 215,697	$ 193,585	$ 251,338	$ 223,578
Weighted average common shares outstanding - basic (in shares)	112,882	112,638	112,855	112,616
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	341	241	303	255
Weighted average common shares outstanding — diluted (in shares)	113,223	112,879	113,158	112,871
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.91	$ 1.72	$ 2.23	$ 1.99
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.91	$ 1.71	$ 2.22	$ 1.98