Income Taxes - Reconciliation Between U.S. Federal Income Tax Rate and Our Effective Tax Rate From Continuing Operations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	3.70%	2.60%	1.70%
Gain on APAC JV ownership changes	(0.20%)	(9.90%)	0.00%
APAC investment impairment	6.40%	0.00%	0.00%
Impact of 2017 Tax Act	(20.50%)	0.00%	0.00%
Other	2.00%	1.80%	2.30%
Impact of noncontrolling interests primarily attributable to non-tax paying entities	(3.30%)	(2.90%)	(8.90%)
Effective tax rate	23.10%	26.60%	30.10%