Amendment Flag Change in Fair Value of Equity Awards Granted in Prior Years that Vested During Year. Change in Fair Value of Equity Awards Granted in Prior Years that Vested During Year [Member] Mark A. McFarland [Member] Mark A. McFarland [Member] Equity Award Related Adjustments. Equity Award Related Adjustments [Member] Fair Value at Year End of Equity Awards Granted During Year. Fair Value at Year End of Equity Awards Granted During Year [Member] Entity Registrant Name Document Type Entity Central Index Key Cover [Abstract] Fair Value of Equity Awards Granted During Year. Fair Value of Equity Awards Granted During Year [Member] Change in Fair Value of Equity Awards Granted in Prior Years that Were Unvested as of End of Year. Change in Fair Value of Equity Awards Granted in Prior Years that Were Unvested as of End of Year [Member] Todd A. Stevens [Member] Todd A. Stevens [Member]