Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Federal:
Current	$ 15,657	$ 4,810	$ 2,529
Deferred	9,919	25,955	11,142
Total federal	25,576	30,765	13,671
State:
Current	4,567	1,914	1,897
Deferred	19	2,500	4,153
Total state	4,586	4,414	6,050
Total provision for income taxes	30,162	35,179	19,721
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	33,728	35,165	19,459
State taxes, net of federal tax benefit	2,990	3,769	5,420
Percentage depletion deduction	(1,352)	(1,444)	(1,217)
Domestic production deduction	(1,624)	(306)	(2)
Noncontrolling interests	(3,177)	(2,639)	(3,686)
Nondeductible expenses	1,094	219	275
Other	(1,497)	415	(528)
Total provision for income taxes	$ 30,162	$ 35,179	$ 19,721
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax, Percent	35.00%	34.00%	35.00%
State taxes, net of federal tax benefit, Percent	3.10%	3.60%	9.70%
Percentage depletion deduction, Percent	(1.40%)	(1.40%)	(2.20%)
Domestic production deduction, Percent	(1.70%)	(0.30%)	(0.00%)
Non-controlling interests, Percent	(3.30%)	(2.60%)	(6.60%)
Nondeductible expenses, Percent	1.10%	0.20%	0.50%
Other, Percent	(1.50%)	0.50%	(0.90%)
Total, Percent	31.30%	34.00%	35.50%
Deferred tax assets:
Receivables				$ 573	$ 332
Inventory				2,212	2,710
Insurance				12,524	10,427
Deferred compensation				12,740	11,139
Other accrued liabilities				2,294	3,405
Accrued compensation				11,031	12,639
Other				2,481	3,410
Net operating loss carryforward				2,341	648
Valuation allowance	$ 641	$ 1,185	$ 3,731	2,153	641
Total deferred tax assets				44,043	44,069
Deferred tax liabilities:
Property and equipment				29,400	30,285
Contract income recognition				20,084	9,455
Total long-term deferred tax liabilities				49,484	39,740
Deferred Tax Liabilities, Tax Deferred Income				(5,441)	0
Net long-term deferred tax (liabilities) assets				0	4,329
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Beginning balance	641	1,185	3,731
Additions (deductions), net	1,512	(544)	(2,546)
Ending balance	2,153	641	1,185
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	1,600
Ending balance	3,300	1,600
Unrecognized Tax Benefits	1,600	1,600		3,300	1,600
Unrecognized Tax Benefits that Would Impact Effective Tax Rate				3,200	1,300
Unrecognized Tax Benefits, Interest on Income Taxes Expense	100	100	900
Unrecognized Tax Benefits, Interest on Income Taxes Accrued				200	100
Other Long Term Liabilities [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	1,578	887	2,231
Gross increases – current period tax positions	1,902	1,006	0
Gross decreases – current period tax positions	(125)	(156)	(282)
Gross increases – prior period tax positions	2	0	0
Gross decreases – prior period tax positions	(5)	0	(2)
Settlements with taxing authorities/lapse of statute of limitations	(90)	(159)	(1,060)
Ending balance	3,262	1,578	887
Unrecognized Tax Benefits	$ 1,578	$ 887	$ 2,231	$ 3,262	$ 1,578