Share-based payments	3 Months Ended
Share-based payments	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based payments	Share-based payments. During the first quarters 2017 and 2016, the Company granted executives and senior management shares of restricted common stock, consisting of time-based shares, which vest on each of the first three anniversaries of the grant date, and performance-based shares, which vest upon achievement of certain financial objectives over the period of three years. The aggregate fair values of these awards at the grant date in the first quarters 2017 and 2016 were $3.0 million (69,000 shares with an average grant price per share of $43.87) and $3.9 million (105,000 shares with an average grant price per share of $37.33), respectively. Awards were made pursuant to the Company’s employee incentive compensation plans and the compensation expense associated with restricted stock awards is recognized over the corresponding vesting period. In April 2017, the Company granted certain senior management 19,000 shares of restricted common stock with aggregate fair value of $0.8 million and an average grant price per share of $44.45. Similar grants were made by the Company in 2016 and were included in the above shares granted during the first quarter 2016.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.