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Subsequent Event	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Event	(11) SUBSEQUENT EVENT The Company entered into a non-binding contract to purchase the Cotter Ranch Tower in Oklahoma City for its corporate headquarters. The contract price is $21.0 million subject to final bankruptcy court approval, which is expected to be announced on or around August 15, 2018.

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- Definition

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

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