Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 193,585	$ 144,145	$ 223,578	$ 162,063
Weighted average common shares outstanding - basic (in shares)	112,638	112,337	112,616	112,381
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	241	314	255	353
Weighted average common shares outstanding — diluted (in shares)	112,879	112,651	112,871	112,734
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.72	$ 1.28	$ 1.99	$ 1.44
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.71	$ 1.28	$ 1.98	$ 1.44