Income Taxes (Income Tax Expense Reconciliation to Federal Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory federal income tax	$ 173,572	$ 102,967	$ 106,101
Less federal income tax assumed directly by noncontrolling interests	(76,364)	(66,783)	(64,219)
State income taxes, net of federal income tax benefit	11,604	6,616	5,539
Increase in valuation allowances	317	4,662	924
Interest related to unrecognized tax benefits	(548)	(161)	(155)
Other	5,209	802	464
Income tax expense	$ 113,790	$ 48,103	$ 48,654