Noncontrolling Interests - Summary of Mandatorily Redeemable Noncontrolling Interests in Other Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mandatorily Redeemable Noncontrolling Interests
Beginning balance	$ 11,511
Redemption value change	2,415	$ 958	$ 1,210
Purchase of noncontrolling interests	(4,173)	(690)	30
Distributions to noncontrolling interest partners	(3,309)	(2,468)	(2,281)
Ending balance	11,615	11,511
Securities Subject to Mandatory Redemption
Income Statement Impact
Noncontrolling interest expense	1,613	1,447	1,625
Redemption value change	446	229	312
Mandatorily Redeemable Noncontrolling Interests
Beginning balance	8,588	9,405	9,355
Redemption value change	2,059	1,676	1,937
Formation of noncontrolling interests	804
Sale of noncontrolling interests	268
Purchase of noncontrolling interests		(803)
Distributions to noncontrolling interest partners	(1,410)	(1,250)	(1,418)
Currency translation adjustment	70	(440)	(469)
Ending balance	10,379	8,588	9,405
Redeemable Partnership Interests
Income Statement Impact
Noncontrolling interest expense	1,571	958	1,226
Redemption value change	844	0	(16)
Mandatorily Redeemable Noncontrolling Interests
Beginning balance	11,511	11,077	10,678
Redemption value change	2,415	958	1,210
Formation of noncontrolling interests		2,062	855
Purchase of noncontrolling interests	(647)	(1,007)	(356)
Distributions to noncontrolling interest partners	(1,664)	(1,579)	(1,310)
Ending balance	$ 11,615	$ 11,511	$ 11,077