Accounting Policies (Policies)	3 Months Ended
Accounting Policies (Policies)	Mar. 31, 2016
Accounting Policies
Revenue Recognition	Revenue Recognition. The Company recognizes revenue for its Lime and Limestone Operations in accordance with the terms of its purchase orders, contracts or purchase agreements, which are generally upon shipment, and when payment is considered probable. Revenues include external freight billed to customers with related costs in cost of revenues. The Company’s returns and allowances are minimal. External freight billed to customers included in first quarter 2016 and 2015 revenues was $5.8 million and $5.2 million, respectively, which approximates the amount of external freight included in cost of revenues. Sales taxes billed to customers are not included in revenues. For its Natural Gas Interests, the Company recognizes revenue in the month of production and delivery.
Successful-Efforts Method Used for Natural Gas Interests	Successful-Efforts Method Used for Natural Gas Interests. The Company uses the successful-efforts method to account for oil and gas exploration and development expenditures. Under this method, drilling, completion and workover costs for successful exploratory wells and all development well costs are capitalized and depleted using the units-of-production method. Costs to drill exploratory wells that do not find proved reserves are expensed.
Comprehensive Income	Comprehensive Income. Accounting principles generally require that recognized revenue, expenses, gains and losses be included in net income. Certain changes in assets and liabilities, such as mark-to-market gains or losses of interest rate hedges, are reported as a separate component of the equity section of the balance sheet. Such items, along with net income, are components of comprehensive income.
Fair Values of Financial Instruments	Fair Values of Financial Instruments. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company uses a three-tier fair value hierarchy, which classifies the inputs used in measuring fair values, in determining the fair value of its financial assets and liabilities. These tiers include: Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; Level 2, defined as observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. There were no changes in the methods and assumptions used in measuring fair value.
New Accounting Pronouncements	New Accounting Pronouncements. In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”), in order to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet for many leases classified as operating leases under previous accounting principles generally accepted in the United States of America. ASU 2016-02 requires that a lessee should recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term on the balance sheet. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 (including interim periods within those fiscal years) and early adoption is permitted. The Company is currently evaluating the impact of adoption of ASU 2016-02 on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718), (“ASU 2016-09”). ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016 (including interim periods within those fiscal years) and early adoption is permitted. The Company is currently evaluating the impact of adoption of ASU 2016-09 on its consolidated financial statements.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.