Long-Term Incentive Plan (Equity-Based Incentive Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	$ 6,570	$ 3,409	$ 10,717	$ 10,059
G&A Expense [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	6,514	3,378	10,632	9,986
Operating Expenses [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	56	31	85	73
Performance Based Awards [Member] | Two Thousand Fourteen Awards [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	0	979	28	4,388
Performance Based Awards [Member] | Two Thousand Fifteen Awards [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	2,066	926	3,224	2,471
Performance Based Awards [Member] | Two Thousand Sixteen Awards [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	2,592	1,023	3,641	2,143
Performance Based Awards [Member] | Two Thousand Seventeen Awards [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	1,252	0	2,498	0
Time-Based Awards [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Allocation of LTIP expense on consolidated statements of income	$ 660	$ 481	$ 1,326	$ 1,057