Interest Income And Interest Expense (Parenthetical) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2012
Interest Income And Interest Expense [Line Items]
Long-term debt, redemption	$ 795,780	$ 740,136
Stated interest rate	4.25%
Senior notes 5.375%, due 2022 [Member]
Interest Income And Interest Expense [Line Items]
Write-off of debt issuance costs	$ 3,000
Long-term debt, redemption	$ 150,000		$ 150,000
Stated interest rate	5.375%		5.375%