Stockholders' Equity - Reconciliation of beginning and ending common stock outstanding (Details) - shares	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of period	134,706,000
Balance, end of period	136,048,000	134,706,000
Common Stock
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of period	134,706,154	125,279,455
Issuance of common stock	1,286,743	9,251,440
Nonvested share-based awards, net of withheld shares	55,274	175,259
Balance, end of period	136,048,171	134,706,154