Stock-Based Compensation, Non-Vested Stock Option Activity (Details) - Stock Options	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares) | shares	19,289,500
Options granted (in shares) | shares	40,000
Non-vested options, options vested (in shares) | shares	(61,900)
Non-vested options, options forfeited (in shares) | shares	(40,440)
Non-vested options at the end of the period (in shares) | shares	19,227,160
Weighted Average Fair Value at Grant Date
Weighted average fair value at the grant date, options outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 9.73
Weighted average fair value at grant date, options granted (in dollars per share) | $ / shares	10.48
Weighted average fair value at grant date, options vested (in dollars per share) | $ / shares	8.27
Weighted average fair value at grant date, options forfeited (in dollars per share) | $ / shares	9.74
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share) | $ / shares	$ 9.74