Income Taxes - Statutory Federal Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax expense at statutory rate									$ 37,827	$ 25,587	$ 45,943
Non-taxable dividend income									0	(1,587)	(2,116)
Income from non-controlling interest									(1,874)	(7,766)	(7,766)
Loss on retirement of preferred stock									(1,901)	0	0
Valuation allowance									33	(13,542)	(2,693)
Other									154	132	384
Income tax expense	$ 9,912	$ 6,327	$ 13,769	$ 4,231	$ 2,769	$ 7,564	$ (6,368)	$ (1,141)	$ 34,239	$ 2,824	$ 33,752
Statutory tax rate									35.00%	35.00%	35.00%