Basis of Presentation and Summary of Significant Accounting Policies - Noncontrolling Interests (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interests balance January 1	$ 698	$ 692	$ 773
Net income allocable to noncontrolling interests, excluding redeemable noncontrolling interests	116	2,014	1,933
Distributions to noncontrolling interests	0	0	(252)
Noncontrolling interests balance at December 31	698	698	692
Excluding Redeemable Non-Controlling Interests
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net income allocable to noncontrolling interests, excluding redeemable noncontrolling interests	$ 0	$ 6	$ 171