Debt Debt Maturities by Year (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 0
Long-term Debt, Maturities, Repayments of Principal in Year Two	553,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	0
Long-term Debt, Maturities, Repayments of Principal in Year Four	300,000
Long-term Debt, Maturities, Repayments of Principal in Year Five	0
Long-term Debt, Maturities, Repayments of Principal after Year Five	400,000
Long-term Debt	$ 1,253,000