Income Taxes Components of Current and Deferred (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign [Line Items]
Current foreign tax expense	$ 875	$ 761	$ 695
Deferred foreign tax expense	(94,149)	(809)	3,353
Total foreign income taxes	(93,274)	(48)	4,048
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	260,252	(5,833)	131,717
BERMUDA
Foreign [Line Items]
Current foreign tax expense	0	0	0
Deferred foreign tax expense	0	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(4,011)	0	0
UNITED STATES
Foreign [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	125,799	(7,451)	10,985
Current Income Tax Expense (Benefit)	36	(80)	487
Deferred Federal Income Tax Expense (Benefit)	(94,079)	(709)	3,327
Foreign
Foreign [Line Items]
Current foreign tax expense	839	841	208
Deferred foreign tax expense	(70)	(100)	26
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 138,464	$ 1,618	$ 120,732