Redeemable Noncontrolling Interests Activity (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Redeemable noncontrolling interests				$ 218,604				$ 219,331	$ 218,604	$ 219,331
Net earnings									15,026	17,797
Distributions									11,450	18,561
Other										37
Operating income	$ 137,124	$ 164,599	$ 191,531	$ 233,655	$ 161,544	$ 153,354	$ 175,790	$ 231,671	726,909	722,359	$ 657,556
Additions from acquisitions									77,378
Redeemable noncontrolling interests	$ 299,558				$ 218,604				$ 299,558	$ 218,604	$ 219,331