Debt Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 04, 2017
Debt Instrument [Line Items]
Loss on early extinguishment of debt			$ 0	$ 0	$ (7,677)
Credit agreement restrictions to 2018			171,000
8.25% Interest Rate [Member]
Debt Instrument [Line Items]
Principal		$ 150,000
Extinguishment of Debt, Amount		$ 156,200
Stated interest rate, senior notes		8.25%
Loss on early extinguishment of debt		$ 7,700
6.5% Interest Rate [Member]
Debt Instrument [Line Items]
Principal			$ 300,000
Stated interest rate, senior notes			6.50%
6.5% Senior Notes [Member]
Debt Instrument [Line Items]
Principal			$ 300,000	$ 300,000
Stated interest rate, senior notes			6.50%
6.0% Senior Notes [Member]
Debt Instrument [Line Items]
Principal			$ 400,000
Stated interest rate, senior notes			6.00%
Subsequent Event [Member] | 6.5% Senior Notes [Member]
Debt Instrument [Line Items]
Principal						$ 300,000
Extinguishment of Debt, Amount	$ 316,400
Loss on early extinguishment of debt	$ 12,200