Federal Income Taxes - Income and Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
TRS income (loss) before income taxes									$ 16,426	$ 52,522	$ 62,694
(Provision) benefit for income taxes:
TRS net income (loss) before noncontrolling interests									61,470	72,776	65,708
Noncontrolling interests	$ (4,032)	$ (418)	$ 5,952	$ (4,340)	$ (14,415)	$ 5,786	$ (8,237)	$ (44,950)	(2,838)	(61,816)	(84,262)
Net income	$ 24,944	$ 13,285	$ 6,108	$ 19,971	$ 34,236	$ 326	$ 26,155	$ 73,875	64,308	134,592	149,970
TRS [Member]
Income Tax Contingency [Line Items]
TRS income (loss) before income taxes									(3,604)	(1,583)	1,008
(Provision) benefit for income taxes:
Federal									(982)	378	(526)
State and local									423	97	(134)
TRS net income (loss) before noncontrolling interests									(4,163)	(1,108)	348
Noncontrolling interests									8	(9)	(208)
Net income									$ (4,155)	$ (1,117)	$ 140