Consolidation and Nature of Operations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash paid (received) during the period for:
Income taxes, net of refunds	$ 1,834	$ (131,154)
Interest, net of amounts capitalized	84,008	90,707
Significant non-cash investing and financing activities:
Accrued capital expenditures	38,985	19,668
Dividends accrued but not yet paid	$ 65,933	$ 62,656