Schedule II - Condensed Financial Information Schedule II Income Statement (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Income Statements, Captions [Line Items]
Total revenue	$ 280,230	$ 208,080	$ 131,234
Operating Expenses	11,746	9,222	8,630
General and Administrative Expense	20,007	14,552	11,734
Interest Expense	410	367	355
Costs and Expenses	(215,897)	(173,594)	(116,005)
Operating Income (Loss)	64,333	34,486	15,229
Other Nonoperating Income (Expense)	77	1	485
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(64,410)	(34,487)	(15,714)
Income Tax Expense (Benefit)	23,397	14,145	6,009
Net income	41,013	20,342	9,705
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Income (Loss) from Subsidiaries, Net of Tax	40,108	20,786	9,827
Total revenue	40,108	20,786	9,827
Operating Expenses	86	42	88
General and Administrative Expense	130	120	108
Interest Expense	0	1	0
Costs and Expenses	(216)	(163)	(196)
Operating Income (Loss)	39,892	20,623	9,631
Other Nonoperating Income (Expense)	61	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(39,953)	(20,623)	(9,631)
Income Tax Expense (Benefit)	(1,060)	281	(74)
Net income	$ 41,013	$ 20,342	$ 9,705