Income Taxes - Earnings Before Income Taxes and Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings before income taxes:
United States	$ 614,261	$ 520,282	$ 493,311
Foreign	108,904	110,817	115,310
Total	723,165	631,099	608,621
Income tax expense:
Partnership UBT	5,363	8,027	10,042
Corporate subsidiaries:
Federal	291	7,957	12,464
State and local	1,064	661	1,372
Foreign	28,158	26,822	31,273
Current tax expense	34,876	43,467	55,151
Deferred tax (benefit)	(6,557)	1,330	(10,847)
Income tax expense	$ 28,319	$ 44,797	$ 44,304