Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2015
Income Taxes [Line Items]
U.S. federal statutory rate			35.00%
Effective income tax rate	25.80%	15.80%	28.70%	14.30%
Income before income taxes, domestic operations			$ 57,200,000	$ 33,700,000
Income before income taxes, foreign operations			96,000,000	80,800,000
Liabilities for uncertain income tax positions	$ 44,400,000		44,400,000						$ 35,900,000
Cash paid for income taxes			40,400,000	$ 40,500,000
Prepaid tax payments	$ 11,600,000		11,600,000						$ 11,600,000
New York City Department of Finance [Member]
Income Taxes [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions			$ 26,000
California Franchise Tax Board [Member]
Income Taxes [Line Items]
Income Tax Examination, Year under Examination						2013	2012
Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Income Tax Examination, Year under Examination					2014	2013	2012
New York State Division of Taxation and Finance [Member]
Income Taxes [Line Items]
Income Tax Examination, Year under Examination						2013	2012	2011