Debt Interest Expense and Other Debt Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Interest expense, debt			$ 22,096	$ 18,436
Less capitalized interest			285	612
Interest expense	$ 11,276	$ 9,056	21,811	17,824
Cash paid for interest			20,736	17,280
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest expense, debt			10,284	7,488
Senior Notes [Member] | 6.5% Senior Notes [Member]
Debt Instrument [Line Items]
Interest expense, debt			9,757	9,757
Amortization discount and deferred debt issuance costs [Member]
Debt Instrument [Line Items]
Interest expense, debt			1,376	930
Commitment Fees and Other [Member]
Debt Instrument [Line Items]
Interest expense, debt			$ 679	$ 261