Consolidated balance sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets
Cash and cash equivalents	$ 48,595	$ 29,819
Accounts receivable, net	96,515	77,307
Inventories, net	16,137	10,510
Prepaid expenses	3,998	3,465
Derivative instruments	2,152	42,516
Deferred income taxes	9,260	0
Total current assets	176,657	163,617
Property and equipment—at cost, net	69,426	71,290
Oil and natural gas properties, using the full cost method:
Proved	3,258,661	2,860,611
Unevaluated (excluded from the amortization base)	321,477	162,921
Accumulated depreciation, depletion, amortization and impairment	(1,470,090)	(1,290,356)
Total oil and natural gas properties	2,110,048	1,733,176
Derivative instruments	6,403	517
Other assets	35,348	38,952
Total assets	2,397,882	2,007,552
Liabilities and stockholders' equity
Accounts payable and accrued liabilities	134,811	101,598
Accrued payroll and benefits payable	24,246	19,655
Accrued interest payable	24,225	24,131
Revenue distribution payable	25,138	18,152
Current maturities of long-term debt and capital leases	5,334	3,746
Derivative instruments	8,234	436
Deferred income taxes	0	26,872
Total current liabilities	221,988	194,590
Long-term debt and capital leases, less current maturities	1,557,528	1,289,656
Derivative instruments	0	2,192
Stock-based compensation	4,942	3,042
Asset retirement obligations	53,305	46,314
Deferred income taxes	62,855	8,901
Commitments and contingencies (Note 14)
Stockholders' equity:
Preferred stock, 600,000 shares authorized, none issued and outstanding	0	0
Additional paid in capital	424,377	422,434
Retained earnings	72,873	17,186
Accumulated other comprehensive income, net of taxes	0	23,223
Total stockholders' equity	497,264	462,857
Total liabilities and stockholders' equity	2,397,882	2,007,552
Class A Common Stock
Stockholders' equity:
Common stock	0	0
Class B Common Stock
Stockholders' equity:
Common stock	4	4
Class C Common Stock
Stockholders' equity:
Common stock	2	2
Class D Common Stock
Stockholders' equity:
Common stock	3	3
Class E Common Stock
Stockholders' equity:
Common stock	5	5
Class F Common Stock
Stockholders' equity:
Common stock	0	0
Class G Common Stock
Stockholders' equity:
Common stock	$ 0	$ 0